Add option to keep screen on while QD-NG is focused

Would be nice to have an option to keep the screen on while QD-NG is focused.

This would spare users from having to wake up the phone every two minutes of inactivity (this is the idle time I have on my phone) and that way we wouldn't need to extend the system screen off time (which could work for QD-NG, but would keep the screen on for longer time when idle).

I know this is a bit of a battery resources consumer, but could be tweaked perhaps with an extended option of dimming the light to the minimum if the screen wasn't touched for X minutes.

Some Android IRC clients do have the option to keep the screen on but without dimming the light off after a certain amount of time.