generalize the protocol to return errors, etc.

Dependencies

• [2] BKNIUJGY update protocol so driver shows syntax errors
• [3] TNRO6KLZ new live app
• [4] OJLXS67N a prefix for metadata in the manifest

Change contents

• replacement in main.lua at line 276
  [3.7608]→[2.1:20](∅→∅)
  − app.send('ok')
  [3.7608]

  [3.7608]
  + app.send('{}')