Separated idleness options for turning off monitor

[tsujan]

The patch preserves the code integrity and is backward compatible.

The maximum value of each monitor spin-box is set to its corresponding action value when the idle action is different from "Nothing". The reason is that, for example, if the action is "Suspend", it doesn't make sense to turn off monitor after it.

Monitor spin-boxes have a "Disabled" label for their minimum value and an appropriate tooltip.

Closes #232

[tsujan]

@stefonarch
I did my tests under LXQt+kwin_wayland. If you find the time, your tests would be appreciated.

[isf63]

Did a quick test on X11, didn't fix my turn-off monitor problem by chance, yet xset dpms force standby works every time....

Saw nothing wrong on X11 except maybe allowing 01:00 for idle time.

[tsujan]

except maybe allowing 01:00 for idle time.

It's the minimum for idleness actions and "Disabled" for monitor power-off. Minimum values like 30 secs or 01:30 would be confusing to users, especially when they want to use their mouse wheels inside those spin-boxes. Actually, including seconds may be an overdoing, but let's not make a big deal of it ;)

didn't fix my turn-off monitor problem by chance

I don't know what may be the cause of your problem, but I'm reasonably sure it isn't in lxqt-powermanagement. Moreover, this PR is only about the separation; no functionality is changed.

[isf63]

minimum for idleness actions and "Disabled" for monitor power-off

Yes, that's what I meant. I just think 1 minute should be included for monitor power-off, and then below that 'Disabled'. Not a key issue.

[stefonarch]

Didn't find an issue testing, also when using legacy values.
Removing the min:1:30 will need some sed to preserve translations, should be easy.