Consolidate setsubstate_* into setsubstate and use a switch.

Consolidate the functions and add some debugging info. Allows to be
able to set a substate without explicitly knowing what the state is. 


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@318635 65c4cc65-6c06-0410-ace0-fbb531ad65f3