drivers.py -- more font changes, start on the slide problems
filterwheel.py -- wrapped filter commands in try / exception blocks

This allows the filter change window to appear without the filter wheel necessarily working. Also altered the filter editing code to operate almost exactly like Stu's
globals.py -- added default fonts and new filter global

Filter global representing value of filter when "Start" last pressed now added.
slide.py -- minor re-formatting.
uspec.py -- font changes, and to filter in 'Start'

Use lighter font for mutable info. Set a fixed filter name when "Start" is pressed.