Contract 6.36.0

The ranking tools, after the Elixir Gym's second run on them (feedback #174-#177).

• rankings_clans on a mode board says its rating is the event's own, drops the Path of Legends note and says when a board has gone still. rankings_timeline on a mode board says a point is written when only names or clans change, so a closed event keeps writing points (#174).
• When a board's ranks and ratings have not moved since its first snapshot, the note says recording began then: when they last moved before that is unknown, and it no longer says names and clans refreshed on a board with one snapshot (#175).
• board: "trophy" refuses with the reason: the API has served the Trophy Road leaderboard empty for recent seasons. It no longer reads like an unknown location (#176).
• rankings_timeline takes season, as every windowed tool does (#177).

Notes, a refusal and a new argument; no value changes.