SCUBA2/general: generalize and rename _ADD_IMAGES_ to _ADD_IMAGE_COMPS_

To work with PICARD, _ADD_IMAGES_ has been generalized and renamed to
_ADD_IMAGE_COMPS_. The new name is a more accurate reflection of what
the primitive does: it adds together named NDF components and writes
the sum to the corresponding extension in a given output file.

All traces of SCUBA-2-specific code have been removed - the only
difference is that the primitive now must be told the extension name
and corresponding NDF components.

Despite looking like a delete-and-add-new commit, it's really a rename
and edit so I've left the contribution history intact.
SCUBA2/general: rename and general _ALIGN_ARRAYS_ to _ALIGN_IMAGES_

As with the previous commit, this is an update to the SCUBA-2
primitive _ALIGN_ARRAYS_ that removes anything specific to that
instrument to allow more general use.
PICARD: use general primitives instead of SCUBA-2 versions

Use the new generalized primitives for aligning images and add up the
NDF components.

This commit also removes the auto-registration feature for SCUBA-2
images as that would require extensive rejigging of a number of
SCUBA-2 primitives. For now users must register the images before
mosaicking using SCUBA2_REGISTER_IMAGES.
PICARD: move CUPID findclumps methods into JCMT parameter list

Since CUPID can be used on SCUBA-2 and ACSIS data, the findclumps
methods should be determined in the general JCMT parameter
check. Extractor is still supported for SCUBA-2.
SCUBA2/general: generalize and move to general

This primitive was mostly generic but in order for it to be used in
PICARD and SCUBA-2 recipes it needed to be expanded to allow non-SMURF
default config locations.
SCUBA2: update to use general primitives

Replace the previous calls to _ALIGN_ARRAYS_ and _ADD_IMAGES_ to
their new, general counterparts.