New command chat_play added to chan_capi

'chat_play' command allows to play voice messages to conference while music on hold is optionally played to caller.

'chat_play' can be used to provide information about new members and to play announcements.

[isdn-in]
exten => _X.,1,Answer ; Answer the line
exten => _X.,n,Goto(s,1)
exten => s,1,capicommand(clamping|100) ; Activate suppression of DTMF tones
exten => s,n,Playback(record-name) ; Ask for name
exten => s,n,capicommand(rxagc|yes) ; Activate Rx AGC
exten => s,n,Record(/tmp/${UNIQUEID}-info:alaw) ; Record message
exten => s,n,capicommand(rxagc|no) ; Deactivate Rx AGC
exten => s,n,capicommand(chat_play|test|m|/tmp/${UNIQUEID}-info.alaw|1-4) ; Play message to conference,
; play music on hold to caller
exten => s,n,capicommand(chat|test|m|1-4) ; Create/enter conference room 'test'


Please read README.media for details