Merge app_pickupchan with app_directed_pickup, for AST-27.

Initially, this was to be a new feature, with a patch from Switchvox,
 but after discussions, it was noted that this feature already existed in trunk.

The resulting discussions ended in a comment that was along the lines of
 "the patch provided here is a lot smaller than what is already in trunk,
 because it doesn't create a new application and duplicate existing code"

It was decided that these two applications could be easily merged to reduce
 code duplication.  SO, that's what this does.


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@114660 65c4cc65-6c06-0410-ace0-fbb531ad65f3