x11/shotman: add new port
The uncompromising screenshot GUI for Wayland compositors.
shotman takes a screenshot and shows it in a small floating thumbnail window.
The screenshot can then copied with Ctrl+C, deleted with D, or dismissed
with Esc.
shotman is designed to run in response to some global hotkey (e.g.: Super+P,
PrintScreen, etc). It is designed for interactive usage.