Blender Git Loki

Basic solver class, to perform iterative simulation of hair (eventually).

Data from DNA can be copied into a SolverData struct for optimized
solver access. This should happen any time the data layout is changed in
the DNA (points/hairs added or removed), since the solver works on fixed
datasets only. After each time step the solver result can be applied
back to the DNA data for display, tools etc.

It may be beneficial to keep the solver and its data around between time
steps, so the data does not get deleted automatically after applying.
Initializing the data, applying and freeing are separate functions.