Add support for badges to TMBarButton

[msaps]

#387 #238

Support for badges to TMBarButton which can be configured via TMBarItemable. Adds:

• badgeValue: String to TMBarItemable.
• TMBadgeView which displays a label inside a filled elliptical view.
• func layoutBadge(_ badge: TMBadgeView, in view: UIView) to TMBarButton.
• Layout implementations for badges to TMLabelBarButton and TMTabItemBarButton.
• Animation niceness for updating badge values and other item updates.