Fix #812: invalid internalizatin of variables into loop
Variables used in other loop should also be considered in the usage analysis.
Add test
Cleanup & add comments
Merge pull request #814 from sklam/fix_812

Fix #812: invalid internalizatin of variables into loop
Merge branch 'master' of github.com:numba/numba into ndadapt_refactor
Keep (data, shape, strides) together for the llarray ABI.