Changelog:
- Added Theme::replace function
- Added TreeView::changeItem function
- Added TreeView::getNode function
- Added ignoreMouseEvents function to canvas widgets
- Added Panel::setEventBubbling to enable more intuitive event propagation
- Replaced getWidgetAtPosition with getWidgetAtPos
- getWidgetBelowMouseCursor was given a parameter for recursive search
- Textures with different part rects were incorrectly considered equal
- showWithEffect didn't show widget if a hide animation was still playing
- Setting opacity of a SubWidgetContainer didn't work
- SubWidgetContainer didn't support show/hide animations