Repl basics

repl will read in from stdin and output what was typed. What should
be noted is that read_line() from the stdlib does not accept keyboard
interupts and work on a pure rust implementation should be worked on
as soon as possible.

Changes to be committed:
	modified:   src/bin/ion.rs
	modified:   src/lib.rs

src/bin/ion.rs

 extern crate ion;
 
 fn main() {
-    ion::repl()
+    loop {
+        ion::repl()
+    }
 }

src/lib.rs

-pub fn repl() {}
+use std::io;
+
+pub fn repl() {
+    let mut input = String::new();
+    let _unused = io::stdin().read_line(&mut input);
+    println!("You typed: {}", input.trim());
+}