added two testing classes
added black background to Engine2D.panel
Merge branch 'cooper-dev' into cooper-test
made clearing operation in Engine2D.frame() more careful
Merge branch 'cooper-dev' into cooper-test
fixed errors in TestState0
refactored for the assumption that GameState,
not StateManager, will track EngineDetails
removed unnecessary black background from Engine2D.panel
Merge branch 'cooper-dev' into cooper-test
adjusted TestState0 for StateManager/GameState refactor
added left and right movement