cleanup

nifty/domain_object.py

nifty/field.py

nifty/field_types/field_array.py

nifty/operators/linear_operator/linear_operator.py

nifty/spaces/gl_space/gl_space.py

nifty/spaces/hp_space/hp_space.py

nifty/spaces/lm_space/lm_space.py

nifty/spaces/power_space/power_space.py

nifty/spaces/rg_space/rg_space.py