render.py: new CLI plugin for dealing with rendering settings (manual rebase onto metadata52) (rebased onto metadata53)

[atarkowska]

This is the same as gh-4542 but rebased onto metadata53.

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This was the same as gh-4385 gh-4430 but rebased onto metadata52. Now with additional commits.

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See the bin/omero render -h output and the test for expected behavior. Primary driver for the creation of render.py was scripting the rendering settings along with the imports so that everything could be re-done if necessary:

PLATE=$(bin/omero import ... | grep Plate:)
bin/omero render copy Image:1 $PLATE

See IDR/idr-metadata#75 for information on the intended workflow for omero render edit.

Perhaps the main discussion point is the use of yaml/json for these settings, and the implementation of pydict_text_readers.py. load is designed to transparently handle:

• json or yaml (former is stricter on types and is better for generated definitions, the latter is more user friendly if you're crafting it by hand)
• /local/file/paths or remote OriginalFile:Ids
• If you're happy with this design I'll re-use it in the metadata plugin.
• For the future: could have json/yaml write methods which could tie in with the new obj/tree plugin CLI: graph extensions design#31 in which case pydict_text_readers.py should be renamed.

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Additional commits implement omero render edit to allow rendering settings to be set on an image.

• Editing of channel names isn't implemented yet, and tests are pending.
• When testing this plugin I ran into several Too many open files errors on the server, and I'm not sure if it's an error in this code, a system misconfiguration, or an OMERO.server bug

[atarkowska]

--rebased-from #4542