Add KNS adoption tools for Plasma, global, and cursor themes, color schemes, and wallpapers

This adds a small cli helper tool which allows you to list what Plasma
themes are available on the system (and which is the current one), as
well as letting you set a theme as the current. It handles being passed
a full path to the theme, though when that happens it just uses the last
bit of the path as the name of the theme.

The latter part allows it to be used by KNewStuff as an adoption
command, and the changes to the knsrc file makes that happen. There is
also a small change which fixes a discrepancy in the naming of the
Plasma Themes dialog, making it consistent with everywhere else that
references Plasma Themes (not sure why they were called styles here,
guessing a really old copy/paste thing).

Additionally, a similar tool for the color and cursor KCMs are also added by
this patch, and the lookandfeeltool binary built by the global themes kcm is
also modified slightly to accept a full path to a package, and added as
an adoption command for those.

The patch also adds a tool which sets wallpapers, which replaces the
failure-prone dbus command previously used as the kns adoption command.