We need an interface to be able to create/destroy/set/get the
RsvgRectangle and RsvgDimensionData structs via Lua, which were missing
or incomplete.
Documentation was also missing, which has been updated.
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