Add Module::getExpander().

include/engine/Module.hpp

@@ -277,6 +277,9 @@ struct Module {
 	Expander& getRightExpander() {
 		return rightExpander;
 	}
+	Expander& getExpander(bool side) {
+		return side ? rightExpander : leftExpander;
+	}
 
 	// Virtual methods