Python bindings for STIR based on ODL.

Extracted from a stir branch of odl with

git filter-branch --index-filter 'git rm --cached -qr --ignore-unmatch -- . && git reset -q $GIT_COMMIT -- test/tomo/backends/stir_setup_test.py odl/test/largescale/tomo/stir_slow_test.py odl/tomo/backends/stir_bindings.py odl/tomo/backends/stir_setup.py examples/tomo/stir_reconstruct.py examples/tomo/stir_project.py examples/tomo/data/stir/initial.hv examples/tomo/data/stir/initial.v examples/tomo/data/stir/small.hs examples/tomo/data/stir/small.s' --prune-empty -- --all