Support more filetypes / arbitrary file import

Some screenshots from the discord

Since PSD files are already allowed, there is probably no reason not to allow these:



Same, .wav files are not very different from mp3 files:

You get the idea:

The actual issue

Since this gets requested a lot, it is probably worth discussing arbitrary file imports (i.e. allowing any file to be imported, without checking if it's "allowed" first):

This is potentially dangerous though, since the act of opening a file sometimes changes the hash of the file. (for example: when opening a .epub file with calibre, it adds/changes the META-INF/calibre-bookmarks.txt file inside the epub/zip.
This would break hydrus' hash-based system.

So: please discuss: "should hydrus prevent users from importing such files?"

No file, test, or entry point is named. Start by reviewing the arbitrary-import proposal and the EPUB/ZIP hash-integrity example, then trace the existing import and hashing behavior. Done requires an agreed approach for unsupported files that does not undermine the hash-based system.