Variable session in hangup hook

Allows channel variables to be accessible in the api_hangup_hook that gets executed for the channel.

Usage:

<action application="set" data="session_in_hangup_hook=true"/>

See Lua#Special_Case:_env_object for an example of how to use this.

See also:

Implemented By:

Module Name	Source File	Last Revised
core	switch_core_state_machine.c	10468