--python-package should create subdirectories like --java-package does
When generating Python code using `ksc --target=python --python-package=pkg.name.here`, the generated files are placed directly in the output directory. I think it would make more sense if the files would automatically be placed in the correct subdirectories ( `pkg/name/here`), as is done for Java when `--java-package` is specified. Since the generated files contain hardcoded references to `pkg.name.here`, they will not work properly anyway unless they are placed in a directory `pkg/name/here`.

This wouldn't apply to `--python-package=.` - since that generates files with relative imports, they will work in any package, so there's no need to generate a specific directory structure.