Update code to accommodate complex meshes

List of Tasks (suggestion):

- [ ] Rename BSP to SpatialDatabase
- [ ] Change insert methods to receive Object and Envelope
- [ ] Change query methods to return a set of objets
- [ ] Add structure to map envelope to Object
- [ ] Add aabb handling
- [ ] Merge with libgdx

Consider using [gdx objects](https://github.com/libgdx/libgdx/tree/master/gdx/src/com/badlogic/gdx/math/collision) for that (Maybe include them into [propan-commons](https://github.com/Harium/propan-commons)).

Related to: https://github.com/Harium/propan/issues/13

Start with the existing BSP implementation and the related propan issue #13, then review the libgdx collision objects linked in the task description. The checklist describes the target broadly: rename BSP, revise object and envelope APIs, support AABBs, map envelopes to objects, and consider merging the libgdx structures into propan-commons.

Written by the indexing model from the issue text.