This patch adds some new functionality to Stroke and StrokeVertexIterator objects.
For strokes, the reversed method is implemented. it works the same as with other python sequence objects (returns an iterator starting from the end). this in in effect the same as Stroke.stroke_vertices_end().
For StrokeVertexIterator an incremented, decremented and reversed method has been added.
incremented and decremented return a new StrokeVertexIterator object that has been in- or decremented,
reversed returns a new StrokeVertexIterator object that will traverse in the opposite direction.