[REFACTOR] Clean-up quadtree tests
[FEAT] Add tests for Quadtree Box and Point helper classes
[FEAT] 100% Quadtree test coverage
[DOC] Update docs for revised Quadtree
Merge pull request #38 from davegw/quadtree-refactor

[REFACTOR] Add tests for Quadtree Box and Point and update docs for revised Quadtree