Please add trivialib.type-unify

https://github.com/guicho271828/trivialib.type-unify

Small step toward "real" type variables in common lisp. (it wouldn't be slow CLOS, I hope !)

I also changed the documentation of TYPE-R. I know it is reflected to the distribution monthly. This is just for --- say, advertisement. https://github.com/guicho271828/type-r
