Add "ref" module
Add "ffi" module
Remove repeated info from "ffi" module
Add "ref-struct" module
Add "ref-union" module
Add "ref-array" module
Move Type interface from "ffi" module into "ref" module
Add info to README.md
Merge pull request #1033 from loyd/node-ffi

node-ffi (+ ref, ref-array, ref-struct and ref-union)