use regex for "to="

Author: aldehir

common/parsers/harmony.cpp

@@ -55,7 +55,8 @@ void harmony_msg_parser::final() {
 }
 
 void harmony_msg_parser::commentary() {
-    if (builder.try_consume_literal(" to=")) {
+    static const common_regex to(" to=");
+    if (builder.try_consume_regex(to)) {
         user_function();
     }
 }