Custom durations in power options.

[HT-7]

Please let the user set a custom number of minutes for "Turn off the screen when inactive for" and "Suspend when inactive for".

The current presets range from 5 minutes to 3 hours. What if the user wants 4 or 5 hours (240 or 300 minutes)?

In the custom duration window, please also add a drop-down selector for "minutes" and "hours". So the user types in a number and decides between "minutes" and "hours".