Move python code to new starcheck/ directory

Update paths in sandbox_starcheck and starcheck.pl to match new name
and location.
Remove references to old aca_check name in code
Switch to argparse from optparse

Also remove logic for non-optional oflsdir
Rearrange model prediction code

The intent here is to make it easier to make the same outputs using
telemetry instead of the model for pre-2011 products.
Directly use telem for temperatures before Jan 2011
Reorganize import statements
Pass obsid temps from python to Perl as JSON
Remove time/ccd_temp writing from calc_ccd_temps

If using per-obsid temperatures, the time list of temperatures is not needed.
Add handling for obsids with no NPNT

(not sure if this is strictly required, but seems safer)
Fix logic to avoid overwriting tstart/tstop