(closes issue #13144)

(closes issue #13144)
Reported by: murf
Tested by: murf
For: J. Geis

The 'data' field in the ast_exten struct was being
'moved' from the current dialplan to the replacement
dialplan. This was not good, as the current dialplan
could have problems in the time between the change
and when the new dialplan is swapped in.

So, I modified the merge_and_delete code to strdup
the 'data' field (the args to the app call), and
then it's freed as normal.

I improved a few messages; I added code to limit
the number of calls to the context_merge_incls_swits_igps_other_registrars()
to one per context. I don't think having it called
multiple times per context was doing anything bad,
but it was inefficient.

I hope this fixes the problems Mr. Geiss was noting in
asterisk-users, see
http://lists.digium.com/pipermail/asterisk-users/2008-July/215634.html

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@133299 65c4cc65-6c06-0410-ace0-fbb531ad65f3