Readme and clippy cleanups

src/eval.rs

@@ -49,7 +49,7 @@ pub fn eval(ast: &Seg, syms: &mut SymTable) -> Result<Box<Ctr>, Traceback> {
                 }
             },
 
-            Ctr::Lambda(ref l) => return Ok(call_lambda(l, arg_cdr, syms)?.clone()),
+            Ctr::Lambda(ref l) => return Ok(call_lambda(l, arg_cdr, syms)?),
 
             Ctr::Symbol(ref tok) => {
                 let outer_scope_seg_holder: Seg;