Unsupported display servers:
	GNU Hurd TTY   Does it have gamma ramp support?
	The BSD TTY:s  Do they have gamma ramp support?
	Haiku          Haiku does not have gamma ramp support
	Wayland        I do not think Wayland have gamma ramp support
	Mir            I do not think Mir have gamma ramp support

Add hotplug support.

Replace use of atoi and atoll.