Make all public API's return Box<EvalAltResult> to reduce footprint.

src/packages/iter_basic.rs

@@ -1,7 +1,7 @@
 use super::{reg_binary, reg_trinary, reg_unary_mut, PackageStore};
 
-use crate::def_package;
 use crate::any::{Dynamic, Union, Variant};
+use crate::def_package;
 use crate::engine::{Array, Map};
 use crate::fn_register::map_dynamic as map;
 use crate::parser::INT;