add svgs to make phk happy

This really is the wrong way to go, generated files should not live
in the source tree. But lightening the load of phk is more important.

doc/graphviz/cache_http1_fsm.svg

+<?xml version="1.0" encoding="UTF-8" standalone="no"?>
+<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN"
+ "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">
+<!-- Generated by graphviz version 2.38.0 (20140413.2041)
+ -->
+<!-- Title: vcl_center Pages: 1 -->
+<svg width="614pt" height="606pt"
+ viewBox="36.00 36.00 577.54 570.00" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink">
+<g id="graph0" class="graph" transform="scale(1 1) rotate(0) translate(40 566)">
+<title>vcl_center</title>
+<polygon fill="white" stroke="none" points="-4,4 -4,-530 537.544,-530 537.544,4 -4,4"/>
+<!-- acceptor -->
+<g id="node1" class="node"><title>acceptor</title>
+<ellipse fill="none" stroke="black" cx="413.544" cy="-508" rx="40.0939" ry="18"/>
+<text text-anchor="middle" x="413.544" y="-504.3" font-family="Times,serif" font-size="14.00">acceptor</text>
+</g>
+<!-- http1_wait -->
+<g id="node2" class="node"><title>http1_wait</title>
+<ellipse fill="none" stroke="black" cx="413.544" cy="-421" rx="48.1917" ry="18"/>
+<text text-anchor="middle" x="413.544" y="-417.3" font-family="Times,serif" font-size="14.00">http1_wait</text>
+</g>
+<!-- acceptor&#45;&gt;http1_wait -->
+<g id="edge1" class="edge"><title>acceptor&#45;&gt;http1_wait</title>
+<path fill="none" stroke="black" d="M413.544,-489.799C413.544,-478.163 413.544,-462.548 413.544,-449.237"/>
+<polygon fill="black" stroke="black" points="417.044,-449.175 413.544,-439.175 410.044,-449.175 417.044,-449.175"/>
+<text text-anchor="middle" x="465.044" y="-460.8" font-family="Times,serif" font-size="14.00">S_STP_NEWREQ</text>
+</g>
+<!-- CNT_Request -->
+<g id="node4" class="node"><title>CNT_Request</title>
+<ellipse fill="none" stroke="black" cx="123.544" cy="-319" rx="61.1893" ry="18"/>
+<text text-anchor="middle" x="123.544" y="-315.3" font-family="Times,serif" font-size="14.00">CNT_Request</text>
+</g>
+<!-- http1_wait&#45;&gt;CNT_Request -->
+<g id="edge4" class="edge"><title>http1_wait&#45;&gt;CNT_Request</title>
+<path fill="none" stroke="black" d="M365.828,-418.624C301.217,-415.905 190.213,-407.948 157.544,-385 144.546,-375.87 136.143,-360.207 130.942,-346.544"/>
+<polygon fill="black" stroke="black" points="134.25,-345.4 127.702,-337.071 127.627,-347.665 134.25,-345.4"/>
+<text text-anchor="middle" x="213.044" y="-373.8" font-family="Times,serif" font-size="14.00">S_STP_WORKING</text>
+<text text-anchor="middle" x="213.044" y="-358.8" font-family="Times,serif" font-size="14.00">R_STP_RECV</text>
+</g>
+<!-- disembark -->
+<g id="node5" class="node"><title>disembark</title>
+<ellipse fill="none" stroke="black" cx="331.544" cy="-91" rx="48.1917" ry="18"/>
+<text text-anchor="middle" x="331.544" y="-87.3" font-family="Times,serif" font-size="14.00">disembark</text>
+</g>
+<!-- http1_wait&#45;&gt;disembark -->
+<g id="edge5" class="edge"><title>http1_wait&#45;&gt;disembark</title>
+<path fill="none" stroke="black" d="M415.457,-402.989C417.361,-378.708 417.784,-333.462 399.544,-301 393.185,-289.684 382.782,-294.383 376.544,-283 343.071,-221.917 388.812,-191.094 361.544,-127 359.933,-123.214 357.76,-119.538 355.315,-116.079"/>
+<polygon fill="black" stroke="black" points="357.823,-113.612 348.842,-107.992 352.358,-117.987 357.823,-113.612"/>
+<text text-anchor="middle" x="413.044" y="-264.3" font-family="Times,serif" font-size="14.00">Session close</text>
+</g>
+<!-- http1_wait&#45;&gt;disembark -->
+<g id="edge6" class="edge"><title>http1_wait&#45;&gt;disembark</title>
+<path fill="none" stroke="green" d="M422.307,-403.301C437.002,-373.118 463.679,-307.551 449.544,-253 433.475,-190.986 421.974,-174.996 379.544,-127 375.151,-122.031 369.936,-117.349 364.589,-113.125"/>
+<polygon fill="green" stroke="green" points="366.294,-110.032 356.177,-106.886 362.124,-115.654 366.294,-110.032"/>
+<text text-anchor="middle" x="476.044" y="-264.3" font-family="Times,serif" font-size="14.00">Timeout</text>
+</g>
+<!-- hash -->
+<g id="node3" class="node"><title>hash</title>
+<ellipse fill="none" stroke="black" cx="136.544" cy="-18" rx="27" ry="18"/>
+<text text-anchor="middle" x="136.544" y="-14.3" font-family="Times,serif" font-size="14.00">hash</text>
+</g>
+<!-- hash&#45;&gt;CNT_Request -->
+<g id="edge2" class="edge"><title>hash&#45;&gt;CNT_Request</title>
+<path fill="none" stroke="blue" d="M115.322,-29.1756C84.8323,-45.1329 29.8514,-79.2306 7.54392,-127 -22.451,-191.231 49.4699,-261.077 93.1002,-295.8"/>
+<polygon fill="blue" stroke="blue" points="91.1075,-298.684 101.149,-302.065 95.4073,-293.16 91.1075,-298.684"/>
+<text text-anchor="middle" x="63.0439" y="-160.8" font-family="Times,serif" font-size="14.00">Busy object</text>
+<text text-anchor="middle" x="63.0439" y="-145.8" font-family="Times,serif" font-size="14.00">S_STP_WORKING</text>
+<text text-anchor="middle" x="63.0439" y="-130.8" font-family="Times,serif" font-size="14.00">R_STP_LOOKUP</text>
+</g>
+<!-- CNT_Request&#45;&gt;disembark -->
+<g id="edge9" class="edge"><title>CNT_Request&#45;&gt;disembark</title>
+<path fill="none" stroke="blue" d="M114.911,-301.078C102.927,-274.969 85.1119,-224.299 107.544,-190 144.65,-133.264 222.638,-109.177 276.058,-99.084"/>
+<polygon fill="blue" stroke="blue" points="276.832,-102.501 286.063,-97.3019 275.604,-95.6098 276.832,-102.501"/>
+<text text-anchor="middle" x="163.044" y="-223.8" font-family="Times,serif" font-size="14.00">Busy object</text>
+<text text-anchor="middle" x="163.044" y="-208.8" font-family="Times,serif" font-size="14.00">S_STP_WORKING</text>
+<text text-anchor="middle" x="163.044" y="-193.8" font-family="Times,serif" font-size="14.00">R_STP_LOOKUP</text>
+</g>
+<!-- http1_cleanup -->
+<g id="node7" class="node"><title>http1_cleanup</title>
+<ellipse fill="none" stroke="black" cx="287.544" cy="-212.5" rx="60.3893" ry="18"/>
+<text text-anchor="middle" x="287.544" y="-208.8" font-family="Times,serif" font-size="14.00">http1_cleanup</text>
+</g>
+<!-- CNT_Request&#45;&gt;http1_cleanup -->
+<g id="edge10" class="edge"><title>CNT_Request&#45;&gt;http1_cleanup</title>
+<path fill="none" stroke="black" d="M122.518,-300.739C122.631,-286.098 125.264,-265.533 137.544,-253 161.837,-228.206 179.978,-243.845 213.544,-235 221.094,-233.011 229.047,-230.811 236.828,-228.6"/>
+<polygon fill="black" stroke="black" points="237.902,-231.933 246.547,-225.809 235.969,-225.205 237.902,-231.933"/>
+</g>
+<!-- disembark&#45;&gt;hash -->
+<g id="edge3" class="edge"><title>disembark&#45;&gt;hash</title>
+<path fill="none" stroke="blue" stroke-dasharray="1,5" d="M298.022,-77.7947C261.99,-64.6754 205.087,-43.9568 169.339,-30.9408"/>
+<polygon fill="blue" stroke="blue" points="170.446,-27.6192 159.852,-27.4866 168.051,-34.1967 170.446,-27.6192"/>
+</g>
+<!-- waiter -->
+<g id="node6" class="node"><title>waiter</title>
+<ellipse fill="none" stroke="black" cx="376.544" cy="-18" rx="32.4942" ry="18"/>
+<text text-anchor="middle" x="376.544" y="-14.3" font-family="Times,serif" font-size="14.00">waiter</text>
+</g>
+<!-- disembark&#45;&gt;waiter -->
+<g id="edge7" class="edge"><title>disembark&#45;&gt;waiter</title>
+<path fill="none" stroke="green" stroke-dasharray="1,5" d="M342.208,-73.174C347.78,-64.3831 354.705,-53.4564 360.874,-43.7236"/>
+<polygon fill="green" stroke="green" points="363.869,-45.5366 366.266,-35.2165 357.956,-41.7892 363.869,-45.5366"/>
+</g>
+<!-- waiter&#45;&gt;http1_wait -->
+<g id="edge8" class="edge"><title>waiter&#45;&gt;http1_wait</title>
+<path fill="none" stroke="green" d="M409.074,-19.7692C455.061,-22.7818 533.544,-35.8546 533.544,-90 533.544,-320 533.544,-320 533.544,-320 533.544,-361.025 491.641,-388.484 457.357,-404.084"/>
+<polygon fill="green" stroke="green" points="455.714,-400.982 447.931,-408.171 458.498,-407.404 455.714,-400.982"/>
+</g>
+<!-- http1_cleanup&#45;&gt;http1_wait -->
+<g id="edge13" class="edge"><title>http1_cleanup&#45;&gt;http1_wait</title>
+<path fill="none" stroke="black" d="M284.429,-230.778C280.813,-255.928 277.543,-303.29 296.544,-337 313.554,-367.178 346.622,-389.066 373.275,-402.763"/>
+<polygon fill="black" stroke="black" points="371.882,-405.979 382.398,-407.266 374.981,-399.702 371.882,-405.979"/>
+<text text-anchor="middle" x="348.044" y="-315.3" font-family="Times,serif" font-size="14.00">S_STP_NEWREQ</text>
+</g>
+<!-- http1_cleanup&#45;&gt;CNT_Request -->
+<g id="edge12" class="edge"><title>http1_cleanup&#45;&gt;CNT_Request</title>
+<path fill="none" stroke="black" d="M246.12,-225.676C208.748,-236.723 159.343,-251.509 157.544,-253 145.588,-262.907 137.308,-278.12 131.915,-291.339"/>
+<polygon fill="black" stroke="black" points="128.55,-290.345 128.34,-300.938 135.11,-292.788 128.55,-290.345"/>
+<text text-anchor="middle" x="213.044" y="-271.8" font-family="Times,serif" font-size="14.00">S_STP_WORKING</text>
+<text text-anchor="middle" x="213.044" y="-256.8" font-family="Times,serif" font-size="14.00">R_STP_RECV</text>
+</g>
+<!-- http1_cleanup&#45;&gt;disembark -->
+<g id="edge11" class="edge"><title>http1_cleanup&#45;&gt;disembark</title>
+<path fill="none" stroke="black" d="M283.67,-194.346C280.556,-176.557 278.212,-148.404 288.544,-127 291.002,-121.907 294.597,-117.309 298.677,-113.246"/>
+<polygon fill="black" stroke="black" points="301.159,-115.725 306.404,-106.52 296.563,-110.445 301.159,-115.725"/>
+<text text-anchor="middle" x="325.044" y="-145.8" font-family="Times,serif" font-size="14.00">Session close</text>
+</g>
+</g>
+</svg>