Make it possible for logmsgbot to report to more than one channel

Some conversations in #wikimedia-dev end up drifting over to
announcements make #wikimedia-operations the natural place to coordinate
MediaWiki code deployments and their outcomes. logmsgbot isn't especially
noisy, so perhaps the best solution is to have it log to both channels.
This patch modifies the tcpircbot module to make it multi-channel-capable, and
adds #wikimedia-dev to the list of channels logmsgbot should report to.

Includes a few small but unrelated touch-ups to the tcpircbot module.

Change-Id: I0e0209e5c159210e112c07325e6a4023946cedba