Merged all identity maps into one in the unitofwork. identity map now properly works with hierarchies.

Refactorings along with a speed improvement on the Hydrator when processing joined resultsets. Other minor tweaks.

Ported fix for #929 from 0.10 to trunk. Testcase needs to be ported later since the behavior implementation is not useable in trunk atm.

merged fix for #912 from 0.10 to trunk (turned out it was not broken in trunk but i merged the patch & testcase anyway. Other refactorings.