Please remove debug prints from byobu-select-session

Please consider removing the debug print output in the select-session.py script called from byobu-select-session. The output is normally never seen by most users under a default configuration, because of the tmux terminal-overrides setting that prevents the alternate display buffer from being used.

I run byobu with smcup/rmcup active, so it does run in the alternate buffer. When I start byobu, detach, reattach, and detach again, the following is displayed on my primary terminal (outside of byobu):

$ byobu
Attaching: [tmux____1]

Sending variable: ['tmux', 'setenv', '-t', u'1', 'DISPLAY', ':0']
Sending variable: ['tmux', 'setenv', '-t', u'1', 'DBUS_SESSION_BUS_ADDRESS', ...
Sending variable: ... and so on
[detached (from session 1)]
$