Introducing various astobj2 enhancements, chief being a refcount tracing...

Introducing various astobj2 enhancements, chief being a refcount tracing feature, and various documentation updates in astobj2.h, and the addition of standalone utility, refcounter, that will filter the trace output for unbalanced, unfreed objects. This comes from the team/murf/bug11210 branch.

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@114175 65c4cc65-6c06-0410-ace0-fbb531ad65f3