New feature from Davide Cavestro - allow using custom Java object serialization engines on a per-DB basis.

Issue 351: MySQL mode: can not create a table with the column "KEY", and can not open databases where such a table already exists. (KEY is _not_ a keyword.)

Issue 351: MySQL mode: can not create a table with the column "KEY", and can not open databases where such a table already exists. (KEY is now a keyword.)