Discord lines arrive, and say why when they don't

When Discord refuses one line of a timeline cross-post or a clan's activity channel, only that line is skipped now, and the page shows what Discord said; before, the lines after it were dropped too. Lines go to a channel at most about 25 a minute, under Discord's own limit, so a busy war day arrives over a few minutes instead of being cut off. A webhook may end in ?thread_id= to post into one thread, and a forum channel's webhook is refused when you save it, with what to use instead. Migrations 0218, 0219; MCP and JSON API unchanged.