index.html, src/game.js: adding shift left/right controls
index.html, src/game.js: removing buggy shift left/right controls
src/components.js, src/game.js: Allow main game panel to be moved
src/game.js, src/components.js: change MAIN panel data structure, fix snap() bug
src/ui.js, src/constants.js: Add shift left/right buttons, break constants out into separate file