additional magnum importer plugins in python build dependencies

[aclegg3]

Motivation and Context

Python importer used in Habitat-lab requires linked Magnum plugins from Habitat=sim.

How Has This Been Tested

NA

Types of changes

• Docs change / refactoring / dependency upgrade
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have completed my CLA (see CONTRIBUTING)
• I have added tests to cover my changes.
• All new and existing tests passed.

[mosra]

remove StanfordImporter as it doesn't support ASCII ply.

Ah, that's one of my TODOs. I'm not interested in implementing parsing of ASCII PLY files myself, but it could delegate to Assimp for those.

Where do these come from, btw? Is there some Habitat code that writes them? Might be a candidate for refactor / replacement with builtin Magnum PLY export functionality.

What StanfordImporter can do and Assimp can't is import of files with per-vertex semantic IDs. I remember that used to be used quite often, not sure if that's still relevant for current datasets.

[aclegg3]

Thanks for the thoughts on this topic.
I don't think semantic ids in .ply are necessary for python import, but ASCII ply is an easy format for hand-edited or human-readable mesh data. Agreed we generally don't try to use these in practice.