adding support for ueberzug into plugins/preview-tui

Correct umount fusefs on FreeBSD. rel. issue  #848

fixed wrong spelled words

Updated wall plugin to the standard utility file

Fix #835

```Shell
~/src/EFForg/https-everywhere/utils/rewriter/rewriter.js .
```

Ref: https://github.com/EFForg/https-everywhere/tree/master/utils/rewriter

Remove suspicious file

plugins: preview-tui: video thumbnails in preview-tui

fix: small error

Fix the same issue as #81 but with nuke

This reverts commit 9f3fbd93ce.

Update config.yml

use $VISUAL environment variable for plugins

falls back to previous behavior if $VISUAL is not set ($EDITOR then vi)

nuke plugin: use $VISUAL environment variable

falls back to previous behavior if $VISUAL is not set ($EDITOR then vi)