Update `cute`: avoid let-binding of constant list.
Correct English.
Add docstring: `cut` and `cute`.
Add errors: `take`, `drop`, `split-at`.
Add erfi-gauche.el and erfi-gauche-test.el
Bug fix and add test

`erfi:let` should should expand code using `letrec`, but some case it didn't.
Cosmetic change of code
Add erfi-srfi-13.el
Add erfi-misc.el