Uartevent (#393)

* support for uart data event

* updated shims

libs/bluetooth/bluetooth.cpp

@@ -98,6 +98,18 @@ namespace bluetooth {
         return uart->readUntil(ManagedString(del)).leakData();
     }    
 
+    /**
+    * Registers an event to be fired when one of the delimiter is matched.
+    * @param delimiters the characters to match received characters against.
+    */
+    //% help=bluetooth/on-uart-data-received
+    //% weight=18 blockId=bluetooth_on_data_received block="bluetooth|on data received %delimiters=serial_delimiter_conv"
+    void onUartDataReceived(StringData* delimiters, Action body) {
+      startUartService();
+      uart->eventOn(ManagedString(delimiters));
+      registerWithDal(MICROBIT_ID_BLE_UART, MICROBIT_UART_S_EVT_DELIM_MATCH, body);
+    }
+
     /**
      * Register code to run when the micro:bit is connected to over Bluetooth
      * @param body Code to run when a Bluetooth connection is established