Ok, all pepped-up.

Using [prospector](http://prospector.readthedocs.org/en/latest/) (prospector -T --strictness veryhigh), only these errors remain:

> conway_gol (conway_gol.py):
>     L62:19 ConwayGameOfLife.to_cells: pylint - W0142
>     Used * or ** magic

> conway_gol_test (conway_gol_test.py):
>     L9:0 TestCell: pylint - R0904
>     Too many public methods (52/20)

> conway_gol_test (conway_gol_test.py):
>     L22:12 TestCell.test_get_neighbour_cells: pylint - W0212
>     Access to a protected member _get_neighbour_cells of a client cl

> conway_gol_test (conway_gol_test.py):
>     L31:25 TestCell.test_get_next_world: pylint - W0212
>     Access to a protected member _get_next_world of a client class

so, nothing serious.