added serial events

sim/libmbit.ts

@@ -429,6 +429,11 @@ namespace pxsim.serial {
     export function readString(): string {
         return board().readSerial();
     }
+
+    export function onDataReceived(delimiters: string, handler: RefAction) {
+        let b = board();
+        b.bus.listen(DAL.MICROBIT_ID_SERIAL, DAL.MICROBIT_SERIAL_EVT_DELIM_MATCH, handler);
+    }
 }