Add a simple quad tree implementation. Rename projection.Point to geometry.Point.
Also some cleanup of test method names (test_foo -> testFoo). (merges pull request #12)
Remove unneeded "static" qualifier in QuadTree.Item interface (thanks Cyril)
Merge pull request #15 from broady/master

Add IntelliJ project files and Gradle build directory to gitignore.
moved startDemo where it is called only once
changed minSdkVersion to 8
Remove use of deprecated projection.Point
Rename BubbleIconFactory to TextIconGenerator, remove use of enums.
Merge pull request #16 from broady/texticons

Rename BubbleIconFactory to TextIconGenerator, remove use of enums.
PointQuadTree returns a Collection, instead of a Set.
Add an optimization - Bounds.contains(Bounds)
Update Quad Tree tests (Set -> Collection)
Performance tweaks to PointQuadTree (increase max elements, remove "optimisation" for Bounds.contains(Bounds))
Refactor private QuadTree constructor (confusing parameter order)
Add animation utilities + demo.