Revised SYNPHOT.F for different integration routine, removed spline.
Set up SYNPHOT.F for absolute photometry as well as normalized.
Provided option of flux integration or photon counting.
Validated this version by comparison of single orbital longitude with
output of INTEGSP.
This new version requires the filter pass bands to be interpolated to
response values at integer Angstroms. Must be done externally.
The new SYNPHOT.ILS references filters that have that feature.