This updates mod_portaudio to use the new v19 api and also contains
major behavioural changes.  This initial check-in should be tested to find
any obscure use cases that lead to crashes etc...

All of the old api interface commands are now depricated and any attempt to
use them should cause a polite warning asking you to try the new single "pa" command.

New Features:
*) Mulitiple calls with hold/call switching.
*) Inbound calls can play a ring file on specified device. (global and per call)
*) Optional hold music for backgrounded calls. (global and per call)


Example dialplan usage:

<extension name="2000">
  <condition field="destination_number" expression="^2000$">
    <!--if the next 3 lines are omitted the defaults will be used from portaudio.conf-->
    <action application="set" data="pa_ring_file=/sounds/myring.wav"/>
    <action application="set" data="pa_hold_file=/sounds/myhold.wav"/>
    <action application="set" data="export_vars=pa_ring_file,pa_hold_file"/>
    <action application="bridge" data="portaudio"/>
  </condition>
</extension>


Example API interface usage:

call extension 1000
> pa call 1000

call extension 1001 putting the other call on hold
> pa call 1001

swap the calls between hold and active
> pa switch

view the current calls
> pa list

forground the call with id 1 
> pa switch 1

background all calls
> pa switch none

send a dtmf string (1234) to the current call
> pa dtmf 1234

answer the oldest unanswered inbound call
> pa answer

answer the call with id 1
> pa answer 1

hangup the active call
> pa hangup

hangup the call with id 1
> pa hangup 1

get device info
> pa dump

print usage summary
> pa help


USAGE:
--------------------------------------------------------------------------------
pa help
pa dump
pa call <dest> [<dialplan> <cid_name> <cid_num> <rate>]
pa answer [<call_id>]
pa hangup [<call_id>]
pa list
pa switch [<call_id>|none]
pa_dtmf <digit string>
--------------------------------------------------------------------------------

The source of the portaudio v19 library will also be checked in for the 
sake of the build system.




git-svn-id: http://svn.freeswitch.org/svn/freeswitch/trunk@3981 d0543943-73ff-0310-b7d9-9358b9ac24b2