(closes issue #13041)

Reported by: eliel
Tested by: murf

(closes issue #12960)
Reported by: mnicholson

In this 'omnibus' fix, I **think** I solved both
the problem in 13041, where unloading pbx_ael.so
caused crashes, or incomplete removal of previous
registrar'ed entries. And I added code to completely
remove all includes, switches, and ignorepats that
had a matching registrar entry, which should
appease 12960.

I also added a lot of seemingly useless brackets
around single statement if's, which helped debug 
so much that I'm leaving them there.

I added a routine to check the correlation between
the extension tree lists and the hashtab 
tables. It can be amazingly helpful when you have
lots of dialplan stuff, and need to narrow
down where a problem is occurring. It's ifdef'd
out by default.

I cleaned up the code around the new CIDmatch code.
It was leaving hanging extens with bad ptrs, getting confused
over which objects to remove, etc. I tightened
up the code and changed the call to remove_exten
in the merge_and_delete code.

I added more conditions to check for empty context
worthy of deletion. It's not empty if there are
any includes, switches, or ignorepats present.

If I've missed anything, please re-open this bug,
and be prepared to supply example dialplan code.



git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@130145 65c4cc65-6c06-0410-ace0-fbb531ad65f3