Added registerDoctrineMappingType() and getDoctrineMappingType() methods, converted DB2 platform and added some tests, made all platforms work for now

Support Sqlite

Migrated MySQL to Doctrine Type Map

Fixed nasty bug in testcase

Migrated Postgres to support Doctrine Mapping Types

Refactored Oracle Platform to support Doctrine Mapping Types

Refactored DB2 support for Doctrine Mapping Types a little bit