Support models in testing mocks

[Mimickal]

We need some way of specifying models in testing. It needs to be a format with consistent internal representation so we can, for example, specify a known-good final state and test that a function produces that desired result. This format needs to support:

• Object location
• Object rotation (euler or quaternion is fine as long as it's consistent)
• Object scale
• Multiple objects (things like markers, nodes, and armatures)
• Regions
• Texture UVWs
• Smoothing groups

We'll also need to support comparing two of these things with each other, either via a file or a raw string.

Maybe we can use an external file with the .obj format, since .obj is just plain text. @gbMichelle is there anything else I'm forgetting?

[Mimickal]

JMS might actually be the right move here, since we already have ways to work with them and compare them.