remove dtype from spaces

demos/wiener_filter.py

demos/wiener_filter_hamiltonian.py

nifty/domain_object.py

nifty/field.py

...rators/fft_operator/transformations/lmgltransformation.py

...rators/fft_operator/transformations/lmhptransformation.py

...y/operators/fft_operator/transformations/rg_transforms.py

...rators/fft_operator/transformations/rgrgtransformation.py

.../operators/fft_operator/transformations/transformation.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

nifty/spaces/space/space.py

nifty/sugar.py

test/test_field.py

test/test_misc.py

test/test_spaces/test_gl_space.py

test/test_spaces/test_hp_space.py