Should now be a stable API.

• Introduced a new behavior-flag: middleCancel determines if releasing a click from within the inner-radius will trigger the extended selection or the defaultIndex selection.
• ChildRegion is now referred to as Slice throughout the API.
• Style variables now have shorter names that resemble the ButtonStyle naming.
• setDefaultIndex now changes the selectedIndex if it isn't a valid index.
• The complementary callbacks (highlight and hover) are now regrouped within PieMenuCallbacks.
• Integrated rotations: scene2d's rotateBy() method is now supported.
• radius has been renamed to minRadius since it is now a suggested radius for the minimal radius value. In case setFillParent(true) or other size-changing methods are used (Table's fill, for example), the widget will now expand as a scene2d user would expect it to.
• innerRadius now designates a percentage of the radius, instead of an amount of pixels.
• Fixed the flicker resulting from hovering out of a contained Actor.
• selectedColor now used by default if no downColor was set: this is to prevent a flicker when clicking.
• Fixed a few Animated constructors.
• The ShapeDrawer is now instantiated internally.
• The default rules used by ShapeDrawer to determine the amount of sides to draw is now internally overridden with an improved algorithm.
• Added an example for adding Keyboard-Key-Mapping (selection through keyboard) on a PieMenu.