setup.py: drop py_modules entry

It looks like this ended up installing the main PyLink modules twice.

setup.py

@@ -67,9 +67,6 @@ setup(
     # Folders (packages of code)
     packages=['pylinkirc', 'pylinkirc.protocols', 'pylinkirc.plugins', 'pylinkirc.coremods'],
 
-    # Single modules. TODO: consider organizing this into a pylink/ folder
-    py_modules=["classes", "conf", "log", "structures", "utils", "world"],
-
     # Data files
     package_data={
         '': ['example-conf.yml'],