The newly added `:cmp` command can compare the contents of either two
files or two directories.
Works in two ways: If nothing is selected, compares the currently
hovered-over object with that in the other pane.
If things are selected, compares those instead.
For anything markdown or that gets displayed as markdown
(e.g. docx files) in the vifm preview, we now use glow
or bat to display a nicely styled and colored version.
For glow I added a script which tries to detect the
current terminal background between dark/light to
correctly set the color scheme.