Valgrind and generic cleanups.

Started with changing some malloc()s to calloc()s to keep valgrind happy
and avoid uninitialised bytes in crypto-code, and continued with a
couple of log message refining and source cleanup.
cf-serverd: classic protocol authentication messages etc sanitisation.
Lots of cleanups, check all values, got rid of mallocs, added better messages.
Fix 16_cf-serverd lan_open.srv tests to not connect over local loopback.
Do not send or receive negative numbers, might catch potential stack corruption or bad code.
A bit more logging/indentation stuff.
Check header consistency more thoroughly.
Do not cleanup global allocations if threads are still active.
Remove uninitialized buffers as source of entropy.
Small cleanups of the PRNG seeding code.
Add a LOUD warning if entropy is not enough

Should never happen since RAND_poll() is supposed to get as much entropy
as needed from the OS-specific pool.
Message was inaccurate.
Homogenous capitalisation.
Free cleanup.
lowercase
Unchecked malloc should be xmalloc.
Log in verbose which connection threads had to abort because of shutdown.
Merge pull request #1848 from jimis/master

Windows cf-upgrade self-exec fix.
Remove lots of cruft from the default CPPFLAGS

This piece of code has been there since first git commit in 2008. It
refers to a similar bunch of code that modifies LDFLAGS, which has been
removed some time now. So lets remove this piece as well...
Indentation.