This wrapper functions should facilitate the handling of rsvg handles.
Especially unrefing with g_object_unref does not seem to work properly
using the lua bindings.
Add scratch files as a start: merge rsvg.h and rsvg-cairo.h.
Concatenate licenses of rsvg.h and rsvg-cairo.
Remove unnecessary defines, private structs, unused apis
(GIO/GdkPixbuf), etc.
Replace deprecated api functions with glib-object functions
Add headers for glib.h and librsvg/rsvg.h