Replace schema with json structured data

[jspectacular]

Product: OC-SDR

Component: All

Category: Firmware/Middleware

Describe the solution you'd like
Replace schema.c with a json specification; add validation tool to user json specification; automatically generate schema.c file from json.

Is your feature request related to a problem? Please describe.
No, this is an enhancement that will make the schema easier to use and understand.

[jspectacular]

Pre-requisites: PR #155 and PR #162

[jspectacular]

This became PR #180

This should probably stay open until the PR is merged into master. You can automatically close it by adding "closes #148" in the merge commit comment of the PR.