SDL3 D test

Create window and run (pseudo) Conway's game of life (impl. doesn't handle edges correctly iirc). Compiled with embedded C (importC) => .h imports need to be wrapped in .c file.

Caveats

• build.d builds the project (ldc2 -run build.d)
• ldc2 has some llvm builtins deactivated, until than we need to at least declare them (functions are not called)
  tracked here
• some nested C macros disappear (fails on macro concatenating other macros: ##); anything needed is in extras.d
  tracked somewhat here #