project file woahs

Outside of a possible `.rxp` (rx project) file in the future, it may be useful to be able to interface with `.aseprite`, `.ase`
and other raster project files like `.psd`, if not superficially.

Doing so might help in efforts to extend rx, as apart from gifs and tifs, there is seemingly no way to save frame / layer info.
Also working on the same document as those who are less technically savy / prefer aseprite could be handy.