Saves screen brightness dimmed by powerdevil

[LinAGKar]

After a period of inactivity, powerdevil in dims the screen to 1/2, then to 1/8, and the turns it off, and a while after that is suspends. So if you have the screen set to 20% brightness, powerdevil will dim it to 10%, and then to 2.5%, and finally 0%. When the computer then suspends, Tuxedo Control Center saves the last non-zero value, in this case rounded to 3%. When the computer resumes, powerdevil restores the brightness to the correct 20%, however then Tuxedo Control Center comes in and sets it down to the dimmed value of 3%, though this was never what it was actually configured to. This is made even worse if the brightness gets low enough to be rounded to 0 (which should be fixed by #48).

If Tuxedo Control Center is gonna be saving the screen brightness, it needs to be aware of this and only save the value set by the user, not the effective brightness after powerdevil dims the screen. If this is not possible, Tuxedo Control Center shouldn't save screen brightness by default, but there seems to be no way to disable it.