improving local storage handling for settings (incl best scores), per #29, closes #17

Merge pull request #29 from ntwcklng/master

save settings in storage

add storage.js

perf: changing 'Text.getText(..)' to reuse an array instead of churning a new one each time

perf: batching cache behavior for plane propeller

fixing subpar minification on eventemitter3 lib

tweak refactoring in play-intro, per #14

fixing shaking bug, closes #26

fixing bug with detecting DOM-ready

refactoring: moving play-hint elements to screen elements interface (for loading), per #14

refactoring: splitting out retry-screen to its own module, per #14

fixing play-intro-screen refs in game.js, per #14

refactoring: renaming welcome to welcome-screen, per #14

adding strict-mode decl to some files where it was missing