Add a series of kconfigxt modules for PowerDevil

This is the port of KConfigXT for PowerProfiles, without the QML Codebase. The code has been extensively rebased, and I tried to make as low commits as possible, to help review. I know that @ngraham had problems with the loading of the settings using this patch (as it's mostly what the Qml version has, too) and I'm investigating this.

How this works: The KConfigXT modules will try to load settings for Three particcular "supergroups":

• AC
• Battery
• LowBattery

The file used to fetch those settings is the same as the old configuration, so things should work:

    <kcfgfile name="powermanagementprofilesrc">
        <parameter name="profileGroup"/>
    </kcfgfile>


    <group name="KeyboardBrightness" parentGroupName="$(profileGroup)">

This way, if we create a PowerManagementProfile("AC") - we will have the data for the entries inside of the AC group. All of the KConfig / KConfigGroup code is removed from the sources, on this patch, and instead we use a PowerManagementProfile.

this let to some big rewrites on parts of the code that used to do string concatenation and group management manually: those should be reviewed carefully.

If you try this patch and settings don't match, please tell me what side of the settings didn't match, send me a picture of the view, and also drop your configuration files here so I can take a look: I do not have access to keyboardBrigthness, brigthness, kernelProfiles on my laptop so I can't test those.

I think the UI is not optimal - I won't work on nitpicks for the interface, what I'm trying to get here is the correct KConfigXT port. interface nitpicks we can fix later on.

@crossi I'v read the documentation of the settings exporter but I failed to create a script for it, I appreciate any help.

Please ignore the rebase-me commits, this will be squashed.