I got my changes committed.
It now uses xmlReadIO instead of xmlParseFile, so it should handle
'tricky' AKA non-ASCII/ANSI filenames on Windows.
Additionally, it now has an extension for .svgz and the saving and
loading inside of repr-io.cpp handles the compression using zlib
ourselves, so it should work nice on Linux *and* on Windows with not
To do this, I started using the stuff in Inkscape::IO / src/io/*
Take a peek and see if this stuff works for you guys also.