Fixing a Vertex2D bug

Vertex2D weren't rendered anymore, because toArray() hadn't been
updated.
Removing call to __applyFilters

__applyFilters() had been removed, but was still present in the
DisplayObject
Bug with vertex2D

Vertex2D constructor when called with only 2 parameters failed
Added error when message when Vertex2D construction fails
Prefixed private methods from LoadingSet