Fixes text reference migration
Fixes auto update text reference migration

This commit just changes the order of the regexes applied to a text. So,
the automatic update text 'Updated automatically by changing...' is
migrated first. This is required because the general regex does not
respect the specifics the the automatic update text (e.g., the trailing
underscore in '...values within child planning element *123_').
Restores original regex behavior
Adds changelog entry
Merge pull request #679 from opf/fix/text_reference_migration_for_mysql

[FIX] Text reference migration for MySQL