Updating THANKS file to reflect recent contributions
Add aclocal.m4 so that HAVE_EPOLL works
Better warnings when attempting unsupported RTP stream actions
Fixing another GCC warning
Reworking of authorisation code.

* Fix off-by-one error in array size that was causing verifyauth to fail.
* Make auth.c a C++ file and fix up warnings
* Add call debug log to make debugging auth failures easier
Fix memory leaks; re-order the message constructor and destructor to make them less likely in future.
Valgrind points out that SIGKILL can't be caught; remove useless code.