Adding 0842, 0843 to help with 0841 deficiencies

A clean backport of 0841 was not possible due to partial schema
differences in the upgrade.  While we may have planned ahead better,
add 0842 just for 2_3 upgraders which ends up being a no-op for
2_4, and adds ON UPDATE CASCADE for 2_5.

Also, for similar but additional reasons, add 0843, which serves two
purposes:
  1) add ON UPDATE CASCADE to the rest for those upgrading 2_5/master
  2) alter config.z3950_index_field_map for those upgrading from 2_4
     and previous (other lines are no-ops in this case)

Signed-off-by: Dan Wells <dbw2@calvin.edu>
Signed-off-by: Remington Steed <rjs7@calvin.edu>