Better focus lock (thanks nafraf) and support for per-camera focus.
web: Type-cast inputs (fixes #130)
Make sure to cast to int() on focus, just in case.
dev: Tweak focus lock program and focus ordering.

(1) There is some setting that was happening after focus was set that
was clearing AFL. (2) Multi-button actions using press() and release()
must be completed in one lua program and cannot be spread across them.
Merge branch 'focus' of https://github.com/duerig/spreads into duerig-focus

Adjusted formatting

Conflicts:
	spreadsplug/dev/chdkcamera.py
Merge branch 'duerig-focus'