* animation renamed to sprite
* renderable/surface renamed to texture
* added in d2math: Vector2, Vector3, Vector4, Matrix3, Matrix4, Quaternion
* worked a bit on the loading scene, main menu scene
* added `d2common/d2input`, copied input vector logic from hellspawner
* added an `InteractiveComponent` which contains input vector, enable
flag, and callback function
* Added an InputSystem which handles input logic and iterates over
entities with interactive components
* added a mouse cursor scene for rendering the mouse cursor
* made the trademark sprite disappear when left mouse is clicked
* various other small bugfixes in scene systems
* added command line arg for launching ecs impl
* removed render system tests, was causing gl context issues in tests
* fixed all lint errors in d2systems
* reduced boilerplate init code for systems with an update to akara
* fixed a race condition in the render system, added a 1-frame delay
* updated all subscriber systems (due to akara update)
* adding render system test (temporary)
* removed d2common/d2scene, was not the right way to go.
* added components for animation, scale, main viewport, viewport filter
* added interface for scenes, which are extensions of akara.System
* BootStrap is now AppBootstrap, common to game clients and headless
server
* added generic BasicScene struct for common scene functionality
* added game object factory as a system, with single sprite factory
* added update counter system, shows how many times the world updates
per second
* integration test is now the game client test
