CMakefiles and Klassy

[DeltaCopy]

I saw that there is this in the README.

Use klassy for window decorations (I don't know how to use make / cmake, so it'll take a while)

So I thought I could assist here..

I've been able to build Klassy Window decorations alongside Lightly.

With this update. The CMake build instructions downloads the Klassy release artifact, extracts it, patches the Klassy CMakesfile.txt (since that contains a lof of QT5 references which are not required anymore) and builds only the window decorations code. If interested https://cmake.org/cmake/help/latest/module/ExternalProject.html is a good place to start on how to incorporate external projects.

Once built both Lightly and Klassy window decorations are installed on the system.