Add named callgroups/pickupgroups

Add named callgroups/pickupgroups

This patch adds named calledgroups/pickupgroups to Asterisk.  Named groups are
implemented in parallel to the existing numbered callgroup/pickupgroup
implementation.  However, unlike the existing implementation, which is limited
to a maximum of 64 defined groups, the number of defined groups allowed for
named callgroups/pickupgroups is effectively unlimited.

Named groups are configured with the keywords "namedcallgroup" and
"namedpickupgroup".  This corresponds to the numbered group definitions of
"callgroup" and "pickupgroup".  Note that as the implementation of named groups
coexists with the existing numbered implementation, a defined named group of
"4" does not equate to numbered group 4.

Support for the named groups has been added to the SIP, DAHDI, and mISDN channel
drivers.

Review: https://reviewboard.asterisk.org/r/2043

Uploaded by:
	Guenther Kelleter(license #6372)

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@370831 65c4cc65-6c06-0410-ace0-fbb531ad65f3