path_parser.rs: Start implementing a recursive descent parser
path_parser.rs: Start implementing a recursive descent parser

The current parser in C works fine for most cases of SVG in the wild,
but it doesn't fully comply with the BNF specified in the SVG spec.
We'll write a new parser for this.

GNOME/librsvg,GNOME/librsvg,GNOME/librsvg,GNOME/librsvg