keycode(16) returns up-arrow symbol instead of 'shift'

[greim]

A workaround is possible but code like this is no longer possible:

var pressed = keycode(ev);
if ('shift' === pressed) {
  // do something
}

I can provide a PR later if needed. Re-ordering the codes object literal ought to fix it.

[timoxley]

Yep, I think that's the only solution that will have most minor break to compatibility

[timoxley]

Solved in #16.