v0.10.0

• Perfect hashing using hashify crate rather than static gperf generated code.
• Added DkimSignature, ArcAuthenticationResults, ArcMessageSignature and ArcSeal headers.
• HeaderName is non-exhaustive.
• Parse obsolete timezones (#95).
• Fix: Folding ws between "Content-Type:" and "plain/text" leads to empty header (#96).
• Fix: Multiline quoted continuations (closes #92).
• Fix: Deserialize (#93).
• Retain mbox IO errors (#91).
• Hide concrete type behind impl type (#94).
• Removed ludicrous feature, the Rust compiler is smart enough to optimize array lookups.