[2.0] Introduced SQL logging facilities. Made Type constructor private to prevent instantiation and force use of the factory method getType().

[2.0] More general work on the SchemaManager and Platform classes. Making API more complete and adding sqlite and mysql test coverage.

[2.0] Fixed issues discovered during code coverage report generation. Made all ClassMetadata properties public (good reasons, read the class docblock). Performance improvements.

[2.0] Started to implement proxy object handling. Introduced a configuration switch for partial objects (allowPartialObjects) that defaults to TRUE. Setting to FALSE enables proxying and lazy-loading.

[2.0] Ensuring that PersistentCollection instances that are injected by Doctrine can be transparently serialized.

[2.0] Fixes and enhancements to sequence generators. Test suite now runs & passes against postgres. Other minor, unrelated cleanups.