Links to on the form https://www.varnish-cache.org/trac/ticket/<num>
are now https://github.com/varnishcache/varnish-cache/issues/<num>, at
least near the top.

Headings starting with "Changes since" looked redundant, and has been
removed. The result is a slightly more consistent changelog.

with the frame length.

Spotted by: Coverity

One cannot use a counter as boolean when you have both waiters and
read ahead,  if one frame heas been read ahead and one stream is
waiting for another frame, the counter will be zero indicating
no frames should be read.

Fixes #2104.

examine the list of things we can handle, and if not, and we are
looking for strings anyway, convert to string right away.

Really fixes #2205

Fixes #2205.

(url, proto, reason, status etc.) to an empty string.

Fixes #1856

message which either goes into CLI (vcl_init{}) or VSL (all others).

Add a new global counter 'vcl_fail' which counts all VCL_RET_FAIL.