SQLite support / database portability for EnsEMBL

Created by: mjg17

This is my portability work to date. See docs/README.db_portability, and in particular the disclaimer therein :-)

I have verified as far as I can that the test suite still passes under MySQL.

Under SQLite:

• cliHelper.t is skipped - not supported yet
• dbEntries.t fails one test, I suspect this is down to the test rather than the code (autoincrement differences) but further checking required.
• schema.t and schemaPatches.t fail.

All the best Michael