Missing LMAP schedule features

[hmh]

This issue lists a few LMAP schedule features that are likely to be either incompletely implemented, or entirely missing.

Some of these are documented upstream, others might be pending further verification and a proper report upstream.

• event type calendar, optional "start" field (unverified)
  lmapd seems to just ignore it for calendar event types, but does implement the "end" field
• pipelined execution mode (underspecified, would be implementation specific anyway)
• schedule/duration (from lmapd readme)
• calendar/timezone-offset (better implementation would be to only accept "Z")