Changelog:
- Kinematic mode ignores accelerations, that's all
- Update moveable to use kinematic mode and set accel & velocity to zero
when entering gridmove mode
Changelog:
- Add previous velocity in ctransform component
- Add functions to check if a boulder can move left or right when
landing on a boulder
- Adjust system execution order
Since an entity is essentially tied to a manager, put it as a field in
Entity. This means no need to pass entity manager when getting a
component, which is more intuitive.