WorldTree/VoxelTree queries for Voxel/WorldObject/Geodes on Lines, Rays and in Spheres

For #192 
...it will also make "scenegraph" based picking possible and is the basis for the shockwaves

As the title says, this PR extends the old querying-capabilities of the worldtree (which where just asking whether and what geodes are in an AABB) by more geometric-types.

Necessary changes were:
* New template class WorldTreeQuery and VoxelTreeQuery, usable for every geometry that supports a certain implicit interface
* New geometry classes Line and Ray
* Tests for the WorldTreeQuery
* Extension of AABB to cooperate with the new query-api
* Moves VoxelTreeNode from collision/ to voxel/ as this structure is used by both, collision and voxeltree-queries
* nearTo(AABB) added to Geometries for checks whether the query should inspect a geode or worldtreenode. Real intersection-tests are to complicated/performance-hungry. The final intersection test is based on Spheres for which accurate intersection-tests exist, so no accuracy is lost.