Don't use current environment in eval by default

[jcubic]

This works by default:

(let ((x 10)
      (expr '(* x x)))
  (eval expr))
;; ==> 100

Eval should be executed in interaction-environment by default.

It will be a breaking change, but it will conform to the standard. From now on, you will need to use this:

(let ((x 10)
      (expr '(* x x)))
  (eval expr (current-environment)))

If you want the same behavior.