MSSQL:
- Fix bool type
- Fix comparator
- Drop Default constraint before deleting column
- Rename Default constraint to use phpBB's names
- Re-create the indices when changing the type of one column
- Uses varchar instead of varbinary
PostgreSQL:
- Creates auto increment sequences by hand instead of using serial
in order to use phpBB's names
- Drop constraint on unique / primary indices
Oracle:
- Rename indices to use phpBB's names
- Fix string not null behaviour
- Fix broken regex in Oracle driver
- Handle to long indices on Oracle
- Rename auto_increment trigger and sequence
- Automatically lowercase keys in assoc results
PHPBB3-16741
