Basic rendering now complete. Tests.

lib/Image/CairoSVG.pm:

* Debugged rendering code and added a fill/stroke routine based on the
  SVG attributes.
* Add "new_sub_path" for the "M" elements.

t/image-cairosvg.t:

* Add a rendering test using Image::PNG::Libpng.

t/Technical_college.svg:

* This is a test SVG file for rendering.

t/Technical_college.png:

* This is a previously-rendered version of "t/Technical_college.svg"
  in PNG format, used to compare with the output of the rendering.