Finish tests for all Space classes

test/common.py

test/data/gen_lm_space_data.py

test/data/gen_power_space_data.py

test/data/gen_rg_space_data.py

test/data/gl_space.npz

test/data/hp_space.npz

test/data/lm_space.npz

test/data/power_space.npz

test/data/rg_space.npz

test/test_serialization.py

test/test_spaces/test_gl_space.py

test/test_spaces/test_interface.py

test/test_spaces/test_lm_space.py

test/test_spaces/test_power_space.py

test/test_spaces/test_rg_space.py