Adds llvoicecallhandler.cpp
Enables the Group and Avatar Actions requiring the voice refactor.
Adds autoStartCallOnStartup, processAgentListUpdates, startCall, and endCall to LLIMMgr.
Gives llimpanel some LLIMModel functionality to see if a floater was opened with the intent of being a call.
Cleans up LLIMPanel with new functions from the voice refactor.
