Gsoc2016 Keyboard Work Breakdown

Get keyboard events

Possible approaches:

• Install a global event filter or something similar to get all Qt keyboard events. Easier approach, but I think this won't let us differentiate between different physical keyboards.
• Access keyboards with a lower level API.

Reference: http://doc.qt.io/qt-4.8/eventsandfilters.html

don't break tooltips, make them read current keyboard preset.

add CO (if not already existent) to enable/disable controllers (make a special one for keyboard controllers?). this is to keep support for the "enable keyboard shortcuts" option of the options menu.

mixxx currently leaks some keyboard events to Qt. This allows library lists to respond to arrow key presses for example. Do we want this? Better manage this via mapping like Traktro does?