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.
Simplify Makefile so that it does not create cf-upgrade-*.o objects.

The side-effect is that autoconf complains that we changed user-defined
variables. That is not true, because CFLAGS, CPPFLAGS, LDFLAGS are
defined by our configure.ac, because we blatantly ignore recommendations
at:

http://www.gnu.org/software/automake/manual/html_node/Flag-Variables-Ordering.html

The proper thing would be to empty the AM_CFLAGS etc options. But we
first need to refactor our configure.ac to not replace CFLAGS, and then
adjust the rest of Makefiles,
Ugly code has ugly bug.
Merge pull request #1848 from jimis/master

Windows cf-upgrade self-exec fix.