This patch adds a scheduler thread to the core and moves the heartbeat
event to use the new scheduler as an example.

Also The following features are implemented that use this scheduler:

sched_hangup dialplan application:

<action application="sched_hangup" data="+10 normal_clearing bleg"/>

** The cause code is optional and the optional bleg keyword will only hangup the
   channel the current channel is bridged to if the call is in a bridge.

sched_transfer dialplan application:

<action application="sched_transfer" data="+10 1000 XML default"/>

** The last 2 args (dialplan and context) are optional

sched_broadcast dialplan application:

<action application="sched_broadcast" data="+10 playback:/tmp/foo.wav"/>
<action application="sched_broadcast" data="+10 playback!normal_clearing:/tmp/foo.wav"/>

** The optional !<cause_code> can be added to make the channel hangup after broadcasting the file.


sched_hangup api function:

sched_hangup +10 <uuid_string> normal_clearing

** The cause code is optional

sched_transfer api function:

sched_transfer +10 <uuid_string> 1000 XML default

** The last 2 args (dialplan and context) are optional

sched_broadcast api function:

sched_broadcast +10 <uuid_str> playback:/tmp/foo.wav
sched_broadcast +10 <uuid_str> playback!normal_clearing:/tmp/foo.wav

** The optional !<cause_code> can be added to make the channel hangup after broadcasting the file.

The new C functions in the core are documented in the doxeygen.

*NOTE* This commit should satisfy at least 2 bounties on the wiki



git-svn-id: http://svn.freeswitch.org/svn/freeswitch/trunk@4785 d0543943-73ff-0310-b7d9-9358b9ac24b2