scheme-interpreter

1. scheme-interpreter is a program used to interprete
   scheme. There aren't bytecode generated during the
   interpreting but relying on the runtime stack in
   C++

2. command-line test

   >>>　(+ 1 2)
   2

   >>>　(define a 1)

   >>>　(+ a 2)
   3

<<<<<<< HEAD >>> (define (fac n)

(if (= n 1) 1

(* n (fac (- n 1))))) ======= \>\>\>　(define (fac n) 　　　　(if (= n 1) 1 　　　　　(* n (fac (- n 1))))) >>>>>>> f482c658cf18bcf7e6055af9896da006df2788c2

\>\>\>　(fac 10)  
3628800

\#support fraction  
\>\>\>  (+ 2/3 (+ 2 2/3))  
10/3