SCUBA2: Add option to explode CALCQU containers

Exploding the containers allows the Q, U images to be
added to the frame object.  The primitive also adds
a FITS header to allow ORAC-DR to distinguish between
the Q and U images.
SCUBA2: Add domain option to CALCQU primitive
SCUBA2: Add QU image despike primitive

Based on the procedure in pol2cat.py.
SCUBA2: Add QU image background subtraction

Based on the procedure in pol2cat.py.
SCUBA2: Add QU image drift subtraction

Based on the procedure in pol2cat.py.
SCUBA2: Add primitive dealing with QU reference

Based on the procedure in pol2cat.py.
SCUBA2: Add primitive to combine QU images

This primitive makes a Q, U, I cube.  However input of the
I image is not yet implemented so the artificial image
is always used.

Based on the procedure in pol2cat.py.
SCUBA2: Add primitive to run POLVEC

This primitive creates the polarized intensity image and adds
it to the ORAC-DR frame.  The FITS format catalogue is
also created.

Based on the procedure in pol2cat.py.
SCUBA2: Add ADAPTIVE method for extinction

This is to allow a POL-2 recipe to be constructed which
applies extinction correction in the same manner
as pol2cat.py.
SCUBA2: Add _POL2_HELLO_ primitive
SCUBA2: Replace placeholder POL STARE recipe

This calls the recently added SCUBA-2 polarimetry primitives
to perform the basics of the procedure from pol2cat.py.  It
does not yet apply masking or find a suitable intensity
map.
SCUBA2: Change REDUCE_POL_STARE_QL symlink

Symlinked this recipe to REDUCE_SCAN_QL instead of
REDUCE_POL_STARE to allow the quick look to monitor the
noise performance.  This should also prevent it
spending too long trying to run the full
REDUCE_POL_STARE recipe.