v2.0.0

Pulled e6 library into its own package & repo & more.

• Removed container Api for e621 library.
• Overhauled dependencies and exports.
• Misc. improvements
• Hotfix for import bugs
• Added SelectorNotifiers
• Removed alt pull tabs
• Refactored e621 dependencies in preparation for migration to independent package
• Updated deprecated members, minor housekeeping
• Removed bloat from collections
• Added MapNotifier
• Moved e621 to its own package, deprecated members

v2.0.0-beta

Complete rework of dependencies + multiple improvements to e6 API.