* fixed bchannel cleaning race condition with new bchannel state (CLEAN_REQUEST)

* added early bridge-hook, so we know if we need to generate ringing or 
  can take it from the far end chan_misdn channel (if available)
* fixed the issue, that we may not activate the bchannel on PTMP, 
  when we receive ALERTING/PROCEEDING/PROGRESS, only on CONNECT. There might
  be other PTMP devices and we might disturb their bchannel. 



git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@34552 65c4cc65-6c06-0410-ace0-fbb531ad65f3

channels/misdn/isdn_lib.h

@@ -35,6 +35,7 @@ enum bchannel_state {
 	BCHAN_RELEASE,
 	BCHAN_RELEASED,
 	BCHAN_CLEAN,
+	BCHAN_CLEAN_REQUEST,
 	BCHAN_ERROR
 };