av-control v0.99

Deployed 2016-11-04.

• The "Projectors" button is now more accurately labelled "Monitor 1".
• The advanced camera menu (long press on the camera button) now contains manual exposure settings, for greater control over camera shots. Settings are saved in the camera presets.
• Next to the clock at the bottom of the screen is an icon showing the status of the touchscreen's connection with the machine in the power room. A green blob is good; a "network disconnected" icon is bad. Touching the icon will give more details.
• Use avx from PyPI rather than our own local copy.
• Improve test coverage.