Simplified DOM selection

[rglover]

It'd be nice to have some short-hand aliases baked in to Joystick for DOM selection.

For example...

// Old
document.querySelector('.blah');
document.querySelectorAll('.blah');

// Short-hand
$.qs('.blah');
$.qsa('.blah');

No change in behavior, purely an alias. If/when #7 becomes a reality, these could be easily swapped with their native equivalents.