Add Rsvg thumbnailer
Re-add the rsvg thumbnailer, using the librsvg library. It fixes issue #20 (closed).
This plugin displays thumbnailer for .svg and .svgz (SVG compressed) files. Despite support, mime type is listed in 'gdk_pixbuf_get_formats', compressed files are not generated.
This plugin does not use directly GdkPixbuf render, because some functions are deprecated (librsvg >= 2.44.0), so it uses Cairo.
Tested with images found here, compressed local .svg file using gzip, and from Inkscape saved as .svgz file.