Navigation between menus
Clear slot focus on menu change
Add note to Config Menu for no_mouse option
Skip navigation logic if NO_MOUSE is false
Make WidgetSlot to have 3 states. NO_CLICK/CHECKED/ACTIVATED. These can be returned when calling WidgetSlot.checkClick().
Merge branch 'keyboard_input' of https://github.com/igorko/flare-engine into keyboard_input
Add enabled check back
Merge remote-tracking branch 'remotes/upstream/master' into keyboard_input

Conflicts:
	src/WidgetSlot.cpp
Fix constructor parameter
Add 3 more key bindings to work with ActionBar
Simplify drawing selection
Make TabList class more flexible. Use ActionBar items with 3 keyboard buttons.
Use const where needed
Add no_mouse checkbox to tablist
Remove icon position assumptions
Use surface from image to draw slot selection.
Merge pull request #625 from igorko/keyboard_input

Navigate between menus with keyboard