Add support for linked and nested components, fix origins, plus more.

[jaredgonzales]

These changes were made to support more complex Fusion360 models that use various other features of the Fusion API. Primarily to support linked components as well as components that are nested.

As the changes began to grow, other features were added including support for different materials, adding options for exporting to Gazebo, and fixing the location of the origins to be the same in the URDF as shown visually in Fusion.

[cadop]

Thanks for this! I'll take a look soon, but could you check if any of the updates in this branch solve some of the problems you addressed? https://github.com/cadop/fusion360descriptor/tree/fix-scaling

I thought nested components was resolved as well, so thanks for bringing that up. Any chance you have test cases you were using to check the issues that you could upload here?

[jaredgonzales]

Yes I can check against some of the open issues. I anticipate that some changes may need to be made so I should have started with this labeled as a draft. When I began committing new changes I was not keeping track of each change very well so I have to read back through the code to understand my own changes - sorry about the mess. I should have also made a test file but haven't got around to it unfortunately but may have time next week.

I believe the nested components were not working for my purposes because the bodies were all being merged into a single STL and not all joints were being exported if they were nested.