Introduce meta field (1.2.0)

This introduces a content.meta field to our Fediverse related m.room.message events on Matrix. The field is attached to events that are related to notifications, and timeline. The data includes: ['status', 'reblog', 'mention', 'redact', 'unreblog', 'account'] then followed by a notice ID or an account ID. The meta field is listened for, and once encountered, a self-reaction occurs with the related available commands. After the self-reaction, we then listen for a second reaction or (m.annotation), and if given, act on the command specified. The commands which are currently supported include: favorite (👏), reblog (🔃), and redact (🗑). A reply is also listened for, or m.in_reply_to. If a reply is encountered on an event with meta, then a reply is carried out splitting at </mx-reply> , with reaction handling done at MSC2677.