Node server for routing to different systems

[dethe]

We'd like to support multiple languages again in Waterbear, but not directly in the browser. The current plan is to provide a Node server which can be detected at runtime and the server can provide interfaces to things like Arduino, Java robotics, Minecraft, etc.

This depends on #362 to be able to show blocks only when they are valid, and handle loading scripts with blocks that are unsupported.

[CelticMinstrel]

Waterbear doesn't seem to have any problem with loading improperly-formatted blocks (at least when they're outdated versions of existing blocks), which is actually kind of problematic in my opinion, but also suggests that accepting unsupported blocks shouldn't be difficult (if not already possible).

[dethe]

The point isn't to refuse to load the blocks, but to refuse to run them, and provide visual indicators for why.

[CelticMinstrel]

I see. It would be nice if that could also be applied to blocks whose structure has changed from one version to another but are loaded from a gist that used the older structure.

[dethe]

I agree, but I think that has more to do with #425 and #918.