Vandelay: Insufficient Quality Fall-Thru Merge Profile

Vandelay: Insufficient Quality Fall-Thru Merge Profile

When a user selects "Merge On Single Match" or "Merge On Best Match" and
apply a minimum quality ratio, the fall-through profile will be used in
a secondary merge attempt for any records that fail the initial merge
due to insufficient record quality.

This allows the user to choose 2 different outcomes based on record
quality.  For example, you may wish to do a full overlay for all
high-quality records, but only extract subjects or other information
from lower quality records.  This also allows users to do record+copy
imports for high-quality records and copy-only imports for low quality
records (using a no-op merge profile like "replace 901c").

Signed-off-by: Bill Erickson <berick@esilibrary.com>