refs #8183. plotMD mantidplot python function.

plotMD is now a new method in mantidplot. Exposed MDNormalization to python as well.
refs #8183. Hide LineViewerOption.

It does not make sense to expose the log option via the setup dialog for the GUI plot MD option.
refs #8183. Plot many MDWorkspaces.

Change the interface so that it allows many MDWorkspaces to be plotted simultaneously. This is more consistent with the plotSpectrum functionality already implemented.
refs #8183. Default to auto-select.

Default to auto-select the non-integrated axis.
refs #8183. Noisy error reporting.
Merge remote-tracking branch 'origin/feature/8183_plotmd_python'