Fix for nsvg__parseTransform not parsing multiple transformations

nsvg__parseTransform, while parsing all transforms within the transform node, would only apply the last transform parsed. The specific cases I encountered were translations and scales. Whichever was last was the only transformation applied, however they should all be applied: http://www.w3.org/TR/SVG/coords.html#TransformAttribute

Also snuck into this commit were local changes I had for what appears to be a bug in the nsvg__parseRotation which I outlined here: https://github.com/memononen/nanosvg/issues/9

If I can provide any information or improve this further in any way, please let me know.

Bryan