Blender Git Loki

- changed DerivedMesh integration, the fluidsim meshes now
replace the original one. so modifiers now work with them
(apply modifier, or edit mode still work on original mesh).
this should fix the three fluidsim bugs in the tracker.
- fixed stupid makesdna problem (writing "char string[160+80]" isnt
a good idea :)
- changed GUI a bit, now displays an estimate of the required memory,
there's still a problem with redrawing (currently relies on a call
to the derived mesh generation)
- the fluidsim struct changed to store the bounding box,
and the current loaded surface mesh
- temporary simulation files are now removed if env. var.
BLENDER_DELETEELBEEMFILES is not set or zero
- fluidsimSettingsFree now gets properly called when freeing an object