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.

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.

refactorings, a bug fix (#786) and improved performance for the hydration of results from polymorphic queries.

made sure every caller of getIdentifier can handle an array. getIdentifier now always returns an array.

started refactoring to final mapper structure for 1.0. different mapping strategies are factored out as separate strategy classes instead of inheritance.