Add call stack error chain

This allows us to write out errors that follow the call stack and give
locations to where errors originated.

Signed-off-by: Alek Ratzloff <alekratz@gmail.com>

src/compile.rs

@@ -82,12 +82,6 @@ impl<'s> Compile<'s> {
                 Inst::Store(word).into()
             }
             Atom::Word(text) => {
-                // XXX : probably something better than this
-                // Check builtins
-                if text == "." {
-                    return Inst::Print.into();
-                }
-
                 // Look for locally defined symbols first. One can't be found,
                 // then create a local variable. The local variable *should* be
                 // defined already, but sometimes things happen.