Change to ECS framework Ashley
Fix graphics, add gravity
Add apache license for ashley framework
Change coords to use upper left
Change PhysicsSystem to EntitySystem
Update .gitignore, .gitattributes
Make Vector2D inner class of PhysicsSystem
Temporary commit before refactoring
Add collision, jumping, improved graphics
Remove ShapeUtils
Cleanup, add acceleration
Implement improved jumping, building system
Remove ScoreSystem for initial release
Merge branch 'release-1.0.0'