[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)

[2.0] Fixed 4 issues with ProxyGenerator. It was not considering the type hint and it was generating an E_STRICT error with incompatible method declaration. Some cosmetic changes in Query