Migrate swig wrappers out to their individual modules

See the ./wrappers subdirectory for wrapper modules with an example in ./wrappers/example. Moved swig subdirectory to ./wrappers/old_swig, as it is no longer used in the build process, but is needed for further migration work and my be removed entirely after all modules are migrated into their own subdirectories
.
In general I have two line-breaks before the next topic in the CMakeFile, but that's only a minor detail.