This reverts commit 78de6b5752.

Differentiate half-page Ctrl+U/D and pageful PageDN/UP movement keys

Added two scripts to change the wallpaper

The one named "nitrogen" allow to change the wallpaper using
nitrogen. The one named "pywal" allows to change the wallpaper and the
terminal color scheme using pywal.
Both of them need to put the cursor over an image, there's no need to
select the file with space.

1. Support passing files to nnn
2. Enable debug logs much early