Blender Git Loki

Partly fix (unreported) particles not updating correctly when changing settings.

Point-cached particles (those using simulations) would not update at all outside of
first frame, due to PSYS_RECALC_RESET flag being ingnored in `system_step()`...

For some mysterious reasons, udate is still non-fully functional outside of startframe
(e.g. changing face distribution between random and jittered), but at least when choosing
'Vertices' you get particles from verts and not faces!