pbx: Make function and application containers take advantage of being sorted.

* Fixed "core show function" tab completion and token count checking.

* Refactored function and application container handling code to reduce
redundancy.

* Made __ast_pbx_run() return using the defines the caller should expect.
Doesn't change the returned values.  Just made use the defines.


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@381102 65c4cc65-6c06-0410-ace0-fbb531ad65f3