moved dynamic and base modules outside of gtk-2.0 directory

* do not move header files yet as they are mostly used by static bindings
* do not remove pygtk.pth and pygtk.py files yet - there is a debate on moving
  these back to pygtk but you might want to import gio static bindings without
  having to have pygtk installed
* I have not tested this with pygtk, committing it so we can find out if it
  causes any issues with legacy modules and code