Add the new `Proc_*` type `Proc_Int8` as a extension of [`Int8`](http://www.haskell.org/ghc/docs/7.6.3/html/libraries/base-4.6.0.1/Data-Int.html#t:Int8) (see Extended class). See [`byte`](http://processingjs.org/reference/byte) in processing.js.
