Add tests for explosion class
Move Explostion to asteroids namespace
Move functionality from main loop to rendering to increase testability
Refactor drawing of extraDude into rendering method, make extraDude into a local variable
Rename extraDude -> extraShip
Fix bug that caused extra lives to be displayed at wrong position
Check KEY_STATUS in rendering to increase testability
Refactor update of srites into asteroids.Game
Refactor score display into rendering
Refactor call to Text.renderText into rendering.js