Work around issue on Wayland where the window does not show up until
Remove leftover IRRKLING reference
Remove unused includes
Upgrade SDL to SDL2 and att FindSDL2 as a submodule
Add CMake generated files to gitignore.
Move EventReciever into its own file and fix compilation warnings
Update CMake version to 4.0 and set C++20
Remove audioIK as Irrclang is dead