bump 5.1 patch up to 8
rearrange SQL upgrade scripts for patch 8
allow different message to make dbpatch row unique
adjust upgrade scripts for new dbpatch message uniqueness
add SQL for noting within-patch messages in dbpatch table
adjust DB check base class to note checks in dbpatch table
fix DB enum check to note check in dbpatch table
remove Java-side deletion of map property values
remove ill-conceived SQL support for deletion of map property values

introduced only since 5.1 so nobody should yet be relying on this
generate DB triggers for map entry deletion
adjust upgrade scripts for new map value delete triggers
update DB schema footer to match generated changes
correct trigger return value and rename the function
propagate effects of previous commit's trigger change
Merge pull request #2893 from mtbc/trac-970-12317-dbpatch-and-map-value

fix #970, #12317: adjust dbpatch table; delete map values with triggers