Update README on dependencies

Calculation can take very long. Most Unix-ish OSes have utilities to do this.

It was troubling me. Mimicking 'gg' would have been hacky and would need
additional processing... 'g' was free. Who cares even if you press twice? ;)

This commit adds dependencies on file, openssl and cut binaries.

We closely follow the output for stat(1).

Add keybind 'Ctrl-k' to copy the absolute path of the file under the cursor if environment variable NOICE_COPIER is set.

1. Highlight the currently selected item in reverse video.
2. Fix: remember the current item when toggling detail view.

B - Block Device
C - Character Device
D - Directory
E - Executable
F - Fifo
L - Symbolic Link
R - Regular File
S - Socket

1. The detailed view shows file type and size using keybind 'd'. Disabled by default.
2. Option 's' sorts dir entries by descending order of size.

The contents of the directory may be changed from the shell by adding or deleting content. Permissions may have changed too. We must re-populate the contents of the current directory.