Blender Git Loki

- switch to using softbody modifier, controls enabling but does not have
variables, these are still in same place. enable button automatically
makes/enables modifier.
- changed hook to hook modifier conversion to happen on direct link,
required to make sure we don't forget to free any memory for files
saved with 2.38 that have hooks.
- update modifier interface to enforce modifiers with the require-original-
data flag to not move beyond deforming modifiers.
- enforce only one softbody modifier allowed

NOTE: Once again, no modifier stack for lattice yet means softbody for
lattice does not work atm.