Blender Git Loki

Fluid: Bounding boxes for effector objects

This commit adds bounding box support for emission objects - similarly to flow objects. Before, each effector object had to iterate over the entire domain. Bake times of scenes with multiple obstacles improved significantly with this optimization.

Other improvements that were implemented alongside the bbox feature:
- Option for subframe sampling for effector objects
- Option to enable / disable effectors (can be animated)
- Optimization for static objects. If a flow or effector object does not move and the adaptive domain is not in use, the bake time will be optimized further by reusing the flow / effector grids from the previous frame (no recalculation).