Updates to the algorithm schema

See the relevant beat.editor MR for how this started.

The algorithm schema is not specific enough, and needs some changing if the JSON schema tech allows it:

• There should be at least 1 output in the algorithm
• Every group should have at least 1 input (otherwise it's an empty group and should be removed)
• Analyzers maybe should be required to have at least 1 result

I'm pretty sure they are all possible to encode in the JSON schema.