Blender Git Loki

Cleanup: move DerivedMesh wrappers for modifiers further down the hierarchy

The main goal of this patch is to cleanup the interface of every modifier. More specifically the interface of modifiers should be DerivedMesh-free.
Internally some modifiers still use DerivedMesh. However I think it is better when the wrappers are in the modifiers so that higher level functions can use the simplified interface.

This patch removes the applyModifier_DM and applyModifierEM_DM functions. In a previous patch (rB3614d9d) the other functions that used DerivedMesh have been removed.

Reviewers: brecht