Refactor precedence rules

src/format.rs

@@ -5,5 +5,13 @@ pub(crate) use terms::*;
 
 trait Precedence
 {
-	fn precedence(&self) -> i32;
+	fn precedence_level(&self) -> i32;
+}
+
+#[derive(Clone, Copy, Eq, PartialEq)]
+pub(crate) enum Parentheses
+{
+	None,
+	PrecedenceBased(i32),
+	Required,
 }