revamp codomain handling

nifty2go/operators/diagonal_operator/diagonal_operator.py

nifty2go/operators/fft_operator/fft_operator.py

...rators/fft_operator/transformations/gllmtransformation.py

...rators/fft_operator/transformations/hplmtransformation.py

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

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

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

...rs/fft_operator/transformations/slicing_transformation.py

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

nifty2go/spaces/gl_space/gl_space.py

nifty2go/spaces/hp_space/hp_space.py

nifty2go/spaces/lm_space/lm_space.py

nifty2go/spaces/rg_space/rg_space.py