[Feature request] configurable movement keybindings

[mmahmoudian]

It would be nice if the keybindings for movement get configurable. At the moment only arrow keys work, but I'm sure Vim and Emacs users would be super happy to be able to also add their own movements keys.

Alternatively the key bindings can be hard-coded but following bat approach which is enabling all these options simultaneously:

arrow	Emacs	Vim
down	Ctrl-n	j
up	Ctrl-p	k
left	Ctrl-b	h
right	Ctrl-f	l

Although I believe the left and right are not used in general in bmon