v0.2.2

Features

• Add available::*::as_ref
• Add available::*::as_mut
• Add available::*::copied
• Add available::*::cloned
• Add available::*::copied on &mut
• Add available::*::cloned on &mut
• Reduce limit of build-in rules generics argement (not need to implement Debug)
• Unsupport &str deserialize, and when encountering, give the user a reasonable panic tip.
• Reduce limit of impl of Validator
• Reduce limit of impl of RuleList
• Sealed RuleExt trait
• Some painc changed to debug_assert