Ability to map hotkeys

[dracan]

It would be useful to be able to control the app via a presentation clicker. The one I have (Kensington) has 3 buttons which map to page up, next, and b.

Below are the actions that will need mapping:

• Start shuffle (currently just the space key)
• Cancel, ready for the next draw (currently just the escape key)
• Confirm as genuine winner (currently just the enter key)

Note that this should be additional custom mappings - not replacing the current ones. This is because defining these, shouldn't break the current keyboard shortcuts when not using a clicker.

[dracan]

I've added hardcoded hotkeys for this so I can use my Kensington clicker. I'll leave this issue open though, as ideally it should be configurable to support other clickers.