Add support for KDE SC apps and Plasma desktop workspace user settings sync

[MurzNN]

Can you please add support for sync KDE SC apps and Plasma desktop workspace settings?

Most of KDE apps use ~/.config/*rc and ~/.kde/share/config/*rc` files with ini style formatting, also simple files in folders at ~/.config` folder, like other Linux apps.

Also, individual settings can be read via kreadconfig and updated via kwriteconfing commands.

[lra]

See https://github.com/lra/mackup/tree/master/doc#get-official-support-for-an-application

[Kemystra]

Hello, I'm a KDE user.

As far as I know, this is the best list of config files for KDE: kde-configurations

The only thing that we need to do is to go inside every folder, single out any cache/state data/junk folders, and write the needed files/folders into a new application config inside the mackup/application folder.

My only concern would be with downloaded themes. Should we include them as backup?