All kinds of changes to get it ready for UI layouts. This means RNA
and operators should be working correct, but most buttons are still
not actually there yet.
* Added near empty soft body, fluid, field and collision panels,
tweaks to cloth panels.
* Fluid bake works, but without escape or showing any progress.
* Fluid/Softbody/Cloth/Collision can now be both added as modifiers
or in the physics panels.
* Missing: fields & soft body for particles.
* Missing: proper updating softbodies, guess this code still needs
updates after pointcache refactor?
