So here is a second version of the patch. But it adds a few more extensions to the list
I forgot about them, as I don't use or experimented with them, but I figured that
this is a good opportunity to add the support for those extensions also.
A small comment for those who are interested, the CBZ (and by mupdf unsupported CBR)
files seem to be just zipped/rarred collections of image files (I guess usually png/jpg). So
supporting those extensions doesn't really require the `mutool` command if emacs would
just uncompress the collections.
I guess there is not much more to comment on in addition to the comments within the patch/files.