[2.0][DDC-49][DDC-50][DDC-33] Fixed DDC-49 and DDC-50. Also addressed DDC-33. Various other small changes and fixes. For problems with proxy objects please refer to the updated documentation.

[2.0] DBAL cleanups (DDC-46). Proxy class improvements (DDC-19, DDC-39). Started new UPGRADE_TO document for upgrade instructions between advancing Doctrine 2 versions.

[2.0] Accomodate joincolumn names in the metadata, in the selection and the hydration processes. Improved Api of the ProxyFactory. Working implementation of lazy loading for *-to-one associations (affects #2348)