Superseding #221 and #228. Eliminate Round Groups; instead have rounds which can have an arbitrary number of metas, and puzzles which can be associated with an arbitrary number of metas from their round.
"isMeta" is a boolean property of puzzles. "feedsMeta" is a list of puzzle IDs. Creating a round creates a puzzle called "#{round} meta". Making a puzzle not a meta removes it from the feedsMeta list of all puzzles in the round. If a round has exactly one meta, new puzzles in the round feed that meta by default, but that can be overridden.
Superseding #221 and #228. Eliminate Round Groups; instead have rounds which can have an arbitrary number of metas, and puzzles which can be associated with an arbitrary number of metas from their round. "isMeta" is a boolean property of puzzles. "feedsMeta" is a list of puzzle IDs. Creating a round creates a puzzle called "#{round} meta". Making a puzzle not a meta removes it from the feedsMeta list of all puzzles in the round. If a round has exactly one meta, new puzzles in the round feed that meta by default, but that can be overridden.