Method/plot odf section

[Gbowker]

This pull request is to allow the user the ability to plot odf sections in place of pole figures with the visualise_volume_element_response task using the method texture_odf_section.

For the time being, I just need to ensure this works, so have replicated any code for plotting pole figures and changing pole_figure to odf_section where applicable.

• Ideally the user may define the euler angle (phi1, PHI, phi2) and value in degrees for this task, but to start with mtex should plot the phi2 45 degree section by default.
• Next, the user should also be able to define whether they would like points on the plot for each orientation or contours representing the ODF. Initially, both options have been set to produce the contured ODF section.

Please comment here for any further suggestions on improvements. Thanks, Guy

[aplowman]

I think you are missing a CLI_format_mapper decorator around multiple_miller_indices_formatter here.