Implement `IntoMint` trait (#68)

* Implement IntoMint trait

* Fix formatting that rustfmt didn't (???)

* Remove IntoMint implementation for primitives

* Remove into_mint method

* Update changelog, bump version, add docs

Release 0.5.6

Add CHANGELOG, bump patch version

More assymetric matrices for vector * matrix notation

SemVer trick for 0.5.0 compatibility

Authors update, expose marker fields

Deriving traits for rotation types