Work around rsvg's inability to parse some tricky SVG pathdata syntax

rsvg has issues with syntax like "M-1-2" and "M.445.483" and
especially "M-.445-.483". Before passing a SVG file contents to it,
tweak all path data to make sure there is at least one space between
numbers, and that leading zero is not omitted.
Merge pull request #1 from MatmaRex/patch-1

Work around rsvg's inability to parse some tricky SVG pathdata syntax