Cast thread_t's all over the place in order to be able to printf them.

A more kosher solution might be pthread_getthreadid_np() on the platforms
which support it, but I can't be bothered for three debugging printfs :-)

Submitted by:	Nils Goroll
Fixes		#932
A quick FlexeLint check to see that there are no major complaints
Match output for boolean params to the default value so
we can choose to present on/off or true/false, depending on what
makes most sense.

Fixes	#1245
Split the http_max_hdr parameter into http_resp_max_hdr and http_req_max_hdr.
Drop counter client_drop_late, it is already counted in sess_drop,
and the counter had race issues.

Polish vsc_f_main.h a bit while here
Revert a5ce9982d87a4398b45886f74306a0ed4d6b1829, there is no
net benefit from hair-splitting the number of http headers we
support.   Improve description to bring this point home, in case
I ever get that silly idea again.
Distinguish between headers we receive (VSL_BogoHeader) and headers
we generate (VSL_LostHeader).

Add counters for requests received with 400, 413 and 417 errors.

Inspired by:	patch from Lasse
Pulling in the request body, is a protocol specific operation,
so move the guts of it from cache_fetch.c to cache_http1_fsm.c.
Make discarding the request body a dedicated function, since
we may be able to orderly terminate/prevent the transmission
in future protocols.