flat is better than nested (cont'd):

- pytest.py is new module, making "python -m pytest" work always
- _pytest/*.py now contains core.py, hookspec and the plugins, no sub packages

doc/example/nonpython/conftest.py

@@ -1,6 +1,6 @@
 # content of conftest.py
 
-import py
+import pytest
 
 def pytest_collect_file(path, parent):
     if path.ext == ".yml" and path.basename.startswith("test"):