Added loc_or_locgroup function

Added loc_or_locgroup function

Intended to to make the shelf_is_group config attribute usefull by
replacing joins to smart_float.config based on copy.location with
joins based on loc_or_locgroup(copy.location). The mapping of multiple
locations to a single group config record works but performance was
significantly slower. Need to speed it up or do something else.

Signed-off-by: Doug Kyle <dkyle@grpl.org>