gpx2svg 0.1.3

I just uploaded the new release 0.1.3 of gpx2svg. It's only a bugfix release. Here are the changes:

• Changed the shebang line so that gpx2svg now also runs on Mac.
• Changed the use of the literal /dev/stdin and /dev/stdout to sys.stdin and sys.stdout. Hopefully, gpx2svg will now also work on Windows (not tested).
• Overall code cleanup