[STUMP] Split monitor

[antithesis]

I'd like to request the feature to split a monitor into multiple monitors,
much like splitting frames. The difference is that each monitor would
display one group. So you have multiple monitors which each contain their
own frames.

The reason why I want this is because there are often windows that I want
to see regardless of the group I'm working in. For example, an IRC client
window that I want to monitor (no pun intended). Another advantage is that
you can dump and load just one part of what's on your screen, namely one
virtual monitor.

I know of one window manager that has a similar feature, and that's
herbstluftwm, written in C. It works a bit different there, as you add a
monitor and define the x and y coordinates, as well as the padding, but
the idea is the same: view multiple tags on the same physical screen.