spore v1.61.0

Added

• Interactions. A spore can hand data to a handler the operator describes, end its turn, and
  read the result when it comes back, as a new message, however much later. The handler does
  whatever it does: shows a page to a person, writes a file a cron job answers, asks another
  system. Spore ships no handler. It defines only the protocol between them, in
  docs/interactions.md.
• config.json takes interactions: each handler by name, as { url, secret, what } or
  { program, what }. A handler at a URL gets signed requests; a program gets the request on
  stdin. Only what reaches a turn, never a URL, a path or a secret.
• spore.cmk takes interactions: <n>, the most one turn may ask, and
  interactions.handlers: [...], the handlers this spore may use. A turn granted a handler
  config.json does not describe is refused when it starts.
• The agent asks through $SPORE_INTERACT (handlers, create <handler> <dir>, status, ls,
  cancel). The runner freezes the data into interactions/<id>/, read-only to the
  agent, and stamps who asked and where the answer goes. spore tick hands over what a handler
  could not take at once.
• The outcome comes back through spore-api, at POST /v1/spores/<name>/interactions/<id>/outcome,
  or on the host through spore interaction outcome <spore> <id> [<file>|-], and from the
  library through interactionOutcome. Spore checks it against what it asked, says it once to
  the conversation the interaction was asked from, and starts a turn to read it.
• A flush's note lists the interactions not yet answered, beside the open question, approvals
  and jobs.

Changed

• The workspace schema is 17. A spore migrates on the first open; an older spore then refuses
  the workspace.