Let rsvg_cairo_clip_render_path use RSVGPathSegm
Don't use moveto segments to determine the directionality of zero-length path segments
Linecaps on zero-length subpaths have no direction
Handle comma's more strictly in path data
Handle comma's more strictly in points
Do not support 'vert' on polygon/polyline.
This should be very rare, as no other renderer supports this.