Code is not licenced for GPL 4

[jriddell]

Many files in this project are GPL 2 or 3 only. There is no "or later" or "later as approved by KDE e.V.".

This goes against the KDE licence policy and means it can not be included in KDE.
https://techbase.kde.org/Policies/Licensing_Policy

It also means that when GPL 4 comes along it won't be able to fix with GPL 4 licenced code.

[facorread]

The specific files with the licensing problem are: src/cursortheme/{{x,}cursortheme,sortproxymodel,thememodel}.{h,cpp} ; Even src/cursortheme/thememodel.cpp is restricted to GPL 2.