Revert back to commit 46f95aa (v0.19.0)

There were several regressions to keybindings on Mac OS X using the
US keyboard layout that this undoes.
Clarify intent of keyIdentifer to charCode mapping
Bring back translation table from @jacobgardner

Ported over from #19
Use translations on Windows
Don't consider keystrokes of 'unset!' bindings for partial matches

Fixes #23
Use keyCode instead of deprecated which
Merge pull request #31 from atom/ks-ns-revert-to-0-point-19

Start over from v0.19.0