Improve WidgetScrollBox
Cleanup headers and allow adding children to WidgetScrollBox
Scroll WidgetListBox when using keyboard controls
Fix memory leak
Add activate() to WidgetScrollBox

This allows us to activate child widgets inside of a WidgetScrollBox via
the keyboard.
Scroll WidgetScrollBox properly when selecting child widgets
Merge pull request #2 from dorkster/scrollbox

Fix child activation and scrolling for WidgetScrollBox
Simplify tab switching in GameStateConfig
Merge pull request #3 from dorkster/scrollbox

Simplify tab switching in GameStateConfig
Remove unneeded code
Merge pull request #605 from dorkster/bugfixes

Scroll WidgetListBox when using keyboard controls
Merge pull request #607 from igorko/scrollbox

Improve keyboard navigation in Config Menu