scripts: Change nxsiv-rifle to uoeia

I rewrote and extended the nsxiv-rifle script recently, and this change
now: removes the old script, adds the new one as a submodule into the
repository and links a working binary into the path.

The new script is essentially still just an image grabber-and-opener,
but supports more image viewers, is a little more advanced and can for
example replace arbitrary parts of urls (and is documented a little more
nicely).

Make qutebrowser use new script and remove leftover references to
nsxiv-rifle. Qutebrowser also gets a third option of viewing images, now
there are:

,i -> open selected link in imageviewer
,I -> open current page in imageviewer
,<C-i> -> open selected image in imageviewer

scripts/.local/share/uoeia

@@ -0,0 +1 @@
+Subproject commit 4a2c9d359b941b042c10a610609339a8d7ff3b1c