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

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.

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

Merged r3518:r3700 from branch to trunk. Branch to be deleted, soon. Development continues in trunk.

- unified getDefaultFieldDeclaration(), force DEFAULT NULL when no default is set and the field allows nulls

reverting the reorganization done in 3455-3456 in order to make merging my experimental branch to trunk easier.

Preparation for new organization of code in to sub packages. Changed autoload() to work with new structure.

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Fleshing out functionality of CLI system and changed syntax of migration classes to only required a to parameter since we already know where we are coming from.