Make compilation (--compile ...) works

[thanhnguyen2187]

The end result is to make Camlisp able to compile arbitrary Scheme expressions from input file(s) to working OCaml code in a .ml file. For example, this Scheme function:

(define (fact-iter n)
   (define (iter result n)
     (if (= n 1)
       result
       (iter (* result n) (- n 1))))
   (iter 1 n))

Should be compiled to:

let fact_iter n =
  let rec iter result n =
    if n = 1
    then result
    else iter (result * n) (n - 1)
  in (iter 1 n)

The plan is to compile the parsed Parser.node to Compiler.ocaml_expr.