SCUBA2: Add optional SFP and resolution parms

A new Spectral Filter Profile calibration facility is now supported.
An frequency band and subarray specific  SFP calibration file
may be specified, such as: ../sfp_s8c.sdf

A new resolution parm may be specified
to override the default value of 0.005.
SCUBA2: Add SFP calibration files

The new Spectral Filter Profile calibration files have been added
to "${ORAC_DATA_CAL}/fts/sfp_s$b$a.sdf"
where $b is the band (8:850, 4:450) and $a is the subarray (a,b,c,d).
The spectrum generator primitive has been updated accordingly.