dispatcher: new variant - ds_is_from_list(groupid, uri, mode)

- can match against records in dispatcher groups
- if groupid==1 - will match against all groups
- if uri is empty, then will match against source address (ip, port,
  proto). Otherwise it has to be a full SIP URI value. The matching
  is not taking in consideration any parameter apart of transport
- mode is a bitmask to tell the matching rules
	- if it is 0, will match everything: ip, port and protocol
	- if bit one is set, will skip matching the port
	- if bit two is set, will skip matching the protocol
dispatcher: extended the documentation for ds_is_from_list()