Mutability and Immutability

This release splits the basic interface implementation into two different structures, one mutable and one immutable, giving more freedom into how the data structure can be used.

First release

This is the first release of "mediatype", an [Internet] Media Type and MIME string parser and modeler for Go

This library expands on the builtin "mime" package to provide a model for an "Internet Media Type" normally specified by Content-Type HTTP and MIME header fields, and as specified in RFC 2045.