Eliminate libvarnish.h embedded #includes.

We now have
	<vapi/vs[mcl].h> for the programmatic API

	<vapi/vs[cl]_int.h> for the underlying structure,
			    shared between API and varnishd

the tbl/ subdirectory

This is based on output from some scripts and basic sanity testing.

and external files are included with <...>

crashing child to do so, and then explicitly start it again.

avoid fixed sleeps waiting for the child process to start.

Fixes: #1024

1 thread is a bit on the low side, make the default on RPM based
distros 50.

Please let me know if any of them are way off

Tighten it up with use of semaphores and collapse s1/s2/s3 using
"accept" keyword.