Simplify subgraph composition

[lutter]

Subgraph composition as described in the RFCs so far has two properties that lead to undesirable behavior for users.

• import by subgraph name rather than solely by ID
• delaying reporting of missing imports as errors until query time rather than at deploy time

My notes on how to recast composition to address these two issues can be found in this gist These should be used not just for an implementation, but also to revise the RFC and engineering plans

[leoyvens]

We will eventually want imports by name, but I agree we should keep that as a future extension.

[pmespresso]

hey folks, just trying to get an idea of where this lands in your roadmap right now. This is quite a crucial component we'd need to release Boardroom.info to the community down the road. Would love to help out where possible!