session-recap 0.5.1: a cleaner map, no guessed dates

Changed

• Map layout. Phases run down a rail with their dates right-aligned and a
  phase count and span in the header; the current phase is highlighted. Decisions
  are a lighter list (no boxes), open and paused ones first, with the turned-down
  alternatives and the reason on one line. The Open list shows by default.

Fixed

• Dates a model guessed (after the session's last activity, or out of order) are no
  longer shown; Build map tells the model when the session last ran.
• A recap no longer fails when the host's clock cannot answer, and the progress timer
  stops itself when its host is gone.
• The simulation tests wait for a recap's background work, which made them flaky.