support for buffer packet type (#608)

* support for buffer packet type

* updated description

* updated signature

* added note on json encoding

* adding sendNumbers

* cleanup

* removing 'sendnumbers'

libs/radio/shims.d.ts

@@ -33,6 +33,15 @@ declare namespace radio {
     //% blockId=radio_datagram_send_string block="radio send string %msg" shim=radio::sendString
     function sendString(msg: string): void;
 
+    /**
+     * Broadcasts a buffer (up to 19 bytes long) along with the device serial number
+     * and running time to any connected micro:bit in the group.
+     */
+    //% help=radio/send-buffer
+    //% weight=57
+    //% advanced=true shim=radio::sendBuffer
+    function sendBuffer(msg: Buffer): void;
+
     /**
      * Reads the next packet from the radio queue and and writes it to serial
      * as JSON.
@@ -148,6 +157,14 @@ declare namespace radio {
     //% help=radio/received-string shim=radio::receivedString
     function receivedString(): string;
 
+    /**
+     * Returns the buffer payload from the last packet taken from the radio queue
+     * (via ``receiveNumber``, ``receiveString``, etc) or the empty string if that
+     * packet did not contain a string.
+     */
+    //% help=radio/received-buffer shim=radio::receivedBuffer
+    function receivedBuffer(): Buffer;
+
     /**
      * Returns the system time of the sender micro:bit at the moment when it sent the
      * last packet taken from the radio queue (via ``receiveNumber``,