Classes under "rulesets" have been moved to "rules", and split up into
futher subdirectories matching their library. As a result we can now
better separate the python bindings, so that things that belongs to the
simulation are separeted from things that belongs to the ai.
If an entity is in mode "planted" we should check for any existing
planted entities below it, to see if we should add it on top of them, or
on top of the terrain.
These are useful when you want to represent concave shapes with more
fidelity (since they otherwise would be represented by a convex hull
when on "free" mode).
We do this by using the GImpact shapes. These work, but are resource
intensive. So make sure you don't use too many of these in free mode.
This isn't thouroughly researched though. It might be worth looking into
btCollisionHull, or to alter some of the parameters to fine tune the
simulation.
