* Cleanup thumbnail bar code
- rename thumbnail method names for succinctness
- Get rid of 'updateThumbnailBar' event -- use existing events
- Get rid of 'blockPowerSave' and 'unblockPowerSave' events -- use a
new combined 'onPlayerPlay' and 'onPlayerPause' events which apply to
power save and updating the thumbbar
* Consistent naming for enable/disable methods
The goal here is to remove shortcut handling from the renderer and
unify it all in menu.js and shortcuts.ks (for alternate shortcuts).
I would rather name it "Play" and change to "Pause" when video is
playing, but Electron doesn't support this (yet).
`globalShortcut` will register the shortcut at the OS level, even when
the app is not focused.
Using `localShortcut` would work, but let's put it in the top menu
instead, where all the other shortcuts are.
