Implement game over logic

Refactor the GameTimer into a glorified setTimeout()

Simplify the keybindings
WIP add computed for keybinds

Need to calculate computeds on reactor initialization
Merge branch 'master' into refactor-to-nuclear-0.4.0

Conflicts:
	app/tetris.js
	src/main.js
	src/nuclear/game-actions.js
	src/nuclear/game-core.js
	src/timeout.js
	src/ui/components/board.js
Refactor for NuclearJS 0.4.0-rc

TODO: fix unit tests for new nuclear api
Refactor how keybinds are handled

Move the conditional game status checking logic into an action and make
the keydown event listener simpler
Implement keybind actions and simply event handler more
Upgrade to use Nuclear 0.4.0-rc3

Organize the nuclear directory with cores and actions subfolders

Make the score and status a computed