Use new None output for mml-only output#379

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dpvc merged 3 commits intodevelopfrom

Jan 22, 2018

Commits on Jan 15, 2018

Use NativeMML output for mml-only output
dpvc
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Commits on Jan 20, 2018

Add output jax 'None' for the caase of jsut MathML (or no output).
dpvc
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Commits on Jan 22, 2018

Merge branch 'develop' into issue378
dpvc
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