BibFormat: removal of unneeded bibfmt.id column

• Removes unnecessary bibfmt.id auto-incremented column that was creating problems with auto-increment ID space exhaustion after records were modified and their HB and other formats deleted and subsequently recreated using new auto-incremented ID. Using (record ID, format) as the primary key is enough. (closes #1139)

• Adds new index for bibfmt.last_updated column.