v0.5.0

Other

• move lint definition out of lib.rs and into Cargo.toml
• check for nightly formatting and switch clippy action
• switch to nightly formatting
• remove redundant lockfile generation for tests
• fix whitespace in code comments of BasicConnector
• [breaking] rename contains on string-likes to contains_string
• add 'map' to structural overview and fix typo
• add toc