opening new channels asyncronously.
* (channel_open): Handler method now takes a channel_open_callback
argument.

* src/channel.c (channel_open_response): New class.
(format_global_success): New function.
(do_channel_open_response): New function.
(make_channel_open_response): New function.
(do_channel_open): Moved most processing into do_channel_open
response.

Rev: src/channel.c:1.28
Rev: src/channel.h:1.25