tests/test_nanshe/test_learner.py: Split up 2D and 3D tests so that resources are better managed at setup and teardown. Related to jakirkham/nanshe#238.
tests/test_nanshe/test_learner.py: Split up 2D and 3D tests so that resources are better managed at setup and teardown. Related to jakirkham/nanshe#238.

nanshe-org/nanshe,DudLab/nanshe,DudLab/nanshe,jakirkham/nanshe,jakirkham/nanshe,nanshe-org/nanshe