The global shortcuts were removed in favor of key events
which are only triggered when a widget has focus. This is
necessary to allow different widgets to react differently
to the 'enter' key. The current key configuration is:
search edit focused:
* left/right: decrease/increase card count for selected database card
* enter: add selected card to deck
* ctrl-enter: add selected card to deck sideboard
* ctrl-left/right: decrease/increase card count in sideboard for selected card
database focused: the same as with search edit.
deckview focused:
* left/right: decrease/increase card count for selected deckview card
* enter: increase count for selected deckview card
* delete/backspace: delete selected card from deck
