Fix tune({freq: 0}) misbehaving (0 is false).
Make widget namespace table non-global.
Move widget definitions to separate module from widget framework.
Change zoom-in limit from 100 kHz to 10 kHz.
Enable Twisted and Python logging and use it instead of print statements.

This doesn't do a lot, except that HTTP requests are now logged, but
hopefully will help with better logging/awareness in the future.