Availability of command-line options to get/set brightness, contrast or input

[emoacht]

This is for unsubscribed users only

As I have explained repeatedly in other Issues, the command-line options to get/set the brightness, contrast or input has been part of the add-on features since its beginning. I prioritized implementing and extending this feature over adding the code to limit its use to subscribed users only. Consequently, it has been available to unsubscribed users as well.

Now, I have almost finished implementing all the functionalities I could think of, and I have finally added the code to restrict the use by unsubscribed users.

An unsubscribed user still can use the basic functionalities to get/set the brightness of the last selected monitor as a trial, while all sub-options, except the value to set brightness, will be ignored.

This Issue is related to #437 #464 #467 #573 #585 #624 #625 #626