Connect many feeds

Connect up to 100 feeds in one call, each { url } or { url, auth } for a members-only one, checked on its own and reported added, already or failed, in the order sent: one that fails never stops the others. A failure carries the error code POST /v1/feeds would answer for that address (feed_login_required: send it again with auth). Every keyword of the workspace with readsWorkspaceFeeds (the default) reads these feeds: an item holding its term is one of its mentions, with its matching rules, billed like any mention. Each feed is read every hour; reading it is free. At most 500 a workspace. The first 8 added bring each reading keyword the newest 10 matching items of the last 30 days; the rest start from now.