usdriver.py -- slide changes, expert mode set to 0 before exit.

FocalPlaneSlide object now in slide.py.
drivers.py -- added enable / disable options to Target class
slide.py -- finally got slide going OK

timeout behaviour better, seems to work.
tcs.py -- mapped PA into 0 to 360
uspec.py -- code for freezing run parameters added, Calib too

Now writes Calib when taking bias, flat etc. Run parameters are frozen when start is enabled.