Avoid name clashes with imported submodules and subpackages

[tovrstra]

When you do

from horton import *
grid = ...

there is a name collision that gets picked up by PyLint. One way to avoid this, is to add the following code to every __init__.py file:

from types import ModuleType
for key, val in globals().items():
    if isinstance(val, ModuleType):
        del globals()[key]
del ModuleType

[tovrstra]

P.S. This code can be put in a function.