update to hotkey settings in deck editor tab

removed LEFT/RIGHT increment/decrement while
the card database/quicksearch edit have focus.
LEFT/RIGHT increment/decrement remains while the
deck view has focus.

also, now the card database delegates focus the
quicksearch editor so that any characters typed
while the card database has focus will narrow
the search down using the quicksearch filter.

`control`+`alt`+`-`/`=` now increment/decrement
the mainboard and `control`+`alt`+`[`/`]` now
increment/decrement the sideboard (alt could not
be used alone as OSX inserts special characters
using alt.

cockatrice/src/tab_deck_editor.h

@@ -80,7 +80,6 @@ private:
     DeckListModel *deckModel;
     QTreeView *databaseView;
 
-    KeySignals dbViewKeySignals;
     QTreeView *deckView;
     KeySignals deckViewKeySignals;
     CardFrame *cardInfo;