These changes are in regards to bug 13249, where users are being surprised by the...

These changes are in regards to bug 13249, where users are being surprised by the changes made
to the Set app in trunk/1.6.x, as they come from the 1.4 world. They are only bitten if
they write their AEL dialplan in the 1.4 world, and then carry it over to a trunk/1.6.x
installation where a "make samples" was executed, or where they hand-edited the
asterisk.conf file and added the [compat] category with app_set = 1.6 (or higher).

(this commit does not totally solve 13249, at least not yet)

The change involves issueing a single warning while the AEL file is loading, if:
 1. app_set is present in the config file, and set to 1.6 or higher.
 2. there are double quotes in an assignment statement (eg x = "hi there";)
 3. the warning was not already issued.

The standalone app, aelparse, does not (yet) issue this warning. I'd have to
have it read in the asterisk.conf file, and that's a bit of hassle. I'll add
it if users request it, tho.

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@138815 65c4cc65-6c06-0410-ace0-fbb531ad65f3