• [BREAKING] MessageMapper::map_message changed to MessageMapper::map_msg.
• [BREAKING] fetch and storage moved to seed::browser::service::{fetch, storage},
  but reimported at the lib level. Ie: seed::fetch, and seed::storage.
• Added support for Vec<Attr> and Vec<Style> in view macros.
• App included in prelude.
• [BREAKING] Seed refactored to use async/.await. fetch.rs docs updated.
• Export Attrs, Style, Listener. ie, can import with seed::Style etc.
• Fixed a bug causing the docs not to build.