Proposed Flexible Part Language Extension

[Orion Pobursky]

I basically copy, pasted, and wiki formatted Roland's LDCad spec.

I think you forgot the CONTENT meta, its properties contain the global options like wire thickness for springs etc.

I read the CONTENT META. A couple of thoughts:
- The add fallback is probably not required since I think the generated (to use Travis's more precise terminology) content should always be added to the subfile.
- Since "fallback" isn't needed, is there a good way to fold the path and spring values into their respective metas? Or maybe a new meta for each?