VMODs.  Otherwise jail_unix doesn't allow you to use VMODs.

Lexicographic order is fine, but can lead to interesting things like:

    ================================================================
    Testsuite summary for Varnish trunk
    ================================================================
    # TOTAL: 571
    # PASS:  565
    # SKIP:  6
    # XFAIL: 0
    # FAIL:  0
    # XPASS: 0
    # ERROR: 0
    ================================================================
    Making check in varnishtop
      CC       varnishtop-varnishtop.o
      CC       varnishtop-varnishtop_options.o
      CCLD     varnishtop
    Making check in etc
    Making check in doc
    Making check in graphviz
    Making check in sphinx
    Making check in man

In other words, picking `varnishtop` from somewhere else in the PATH.
Since SUBDIRS are processed sequentially, this is change is enough to
cover parallel builds too.

While at it, polish u4.vtc a bit: get rid of the shell process.

Flexelint comments are mandatory, and must bracket all content
after the initial block comment.

Macros can either be single line "FOO(....)\n" or multiple line
"FOO(...\n)\n\n"

Any macros defined or called must be #undef'ed by the include/tbl file

include/tbl/style.py checks this.

so that our compiled VCLs are certain to restart/reload even if
the VMOD package has been updated in the meantime.

Fixes: #2041

Spotted by:	dridi

Fixes:	#2175

Fixes: #1750

make it work more like people would expect.

Fixes #1991

die until we have started the child process.

what our job is and how we will structure processes for it, before
doing all the complex stuff.

startup situation.

Example for the case addressed here is an html comment which is not esi.

	1st call on !--e
	2nd call on !--end

The first call could match !--esi:, so vep_match() does not return with
VEP_NOTMYTAG, but with null, so characters up until 'e' are marked.

For the second call, we need to consider the case that characters after
the end of the tag could already be marked.

Fixes #1988

ESI Debugging code is disabled unless the Debug macro at the top of the file is changed.