Add support for bracketed paste mode
Add support for bracketed paste mode

The message entry box now allows pasting and sending multi-line
messages.

Requires patched version of urwid:
https://github.com/tdryer/urwid/commit/4406521b55ca97a07cde748ddc02548e62141eb0

See #75.

ddboline/hangups,das7pad/hangups,tdryer/hangups