cmake: Move some functionality from compile.sh to CMakeLists.txt

Purpose:
- Make it simpler to build nwnx2 with an IDE that supports
  CMakeLists.txt, like QtCreator.
- Make it easier to build outside the source directory.

Changes:
- Set library output to compiled, so *.so are copied there
  automatically.
- Create fake build target to force rebuilding the compiled
  directoy.
- Add commands for copying files and concating nwnx2.ini files.