+ Added vertex control labels with following functionality:
	+ 2 available positioning modes: by sides or by coordinates
	+ Always attached to vertex and moves with it
	+ Same template logic as in EdgeLabelControl
+ Added key modifiers to vertex event args
+ Fixed ViewFinder not deriving ZoomControl background
+ Implemented some properties as dependencies
+ Reworked EdgeLabelControl inner logic. Should now be more flexible and performance efficient.