Added support for defining macros in Rust within the macro system

Also fixed a lot of bugs

orchid-std/src/macros/rule/vec_match.rs

@@ -36,7 +36,6 @@ pub fn vec_match<'a>(
 			}
 			None
 		},
-		// XXX predict heap space usage and allocation count
 		VecMatcher::Middle { left, left_sep, mid, right_sep, right, key_order } => {
 			if seq.len() < left_sep.len() + right_sep.len() {
 				return None;