Further edits to documentation

Includes correcting some amusing cut-and-paste errors in Forme::InputsWrapper::Div and its friends, as well as moving the excellent introduction to Forme from "Forme" (the class) to the Readme. Also marked all (hopefully all) the _* commands (_input, _tag, et cetera), as "public but internal",

I'm afraid I'm not sure how to not include the Postgres enumerated type code while still preserving it for my own use.