v0.5.0

• Added extensible enum class (#14)
• Added some asyncpg utilities
• Added basic config validation support to disallow default values
• Added matrix-nio based end-to-bridge encryption helper for bridges
• Added option to use TLS for appservice listener
• Added support for Authorization header from homeserver in appservice transaction handler
• Added option to override appservice transaction handling method
• Split Bridge initialization class into a more abstract Program
• Split config loading