Gross and background now account for flatfield and deadtime effects from epsilon column.  Added additional test to test_cos.py to check the operation
Initial implementation of flux-corrected lightcurve
Divide counts by timestep in flux calibration
Bug in flux-calibration where phottab is only looked for in lref.  Now path$file is expanded
Implemented TDS correction to FLUX column.  Initial tests show very strong agreement to x1d extracted spectra, more formalized tests to follow.

Modified lightcurve script to accept kwargs for step, wmin, wmax.