scratch like broadcast api (#1358)

* scratch like broadcast api

* always register handler

* adding docs

* added icon

* updated block name

* adding DAL support "radio.raiseEvent"

* typo

* implemented using radiobus

* adding docs

* adding raise event block

* updated shims

* updated pxt

libs/radio-broadcast/docs/reference/radio/on-received-message.md

@@ -0,0 +1,45 @@
+# on Received Message
+
+Run part of a program when the @boardname@ receives a
+message over ``radio``.
+
+```sig
+radio.onReceivedMessage(0, function() {})
+```
+
+## Parameters
+
+* **msg**: The message to listen for. See [send message](/reference/radio/send-message)
+
+## Examples
+
+## Example: Broadcasting heart or skull
+
+Sends a ``heart`` message when ``A`` is pressed, ``skull`` when ``B`` is pressed. On the side, display heart or skull for the message.
+
+```blocks
+enum RadioMessage {
+    heart,
+    skull
+}
+input.onButtonPressed(Button.A, function () {
+    radio.sendMessage(RadioMessage.heart)
+})
+input.onButtonPressed(Button.B, function () {
+    radio.sendMessage(RadioMessage.skull)
+})
+radio.onReceivedMessage(RadioMessage.heart, function () {
+    basic.showIcon(IconNames.Heart)
+})
+radio.onReceivedMessage(RadioMessage.skull, function () {
+    basic.showIcon(IconNames.Skull)
+})
+```
+
+## See also
+
+[send message](/reference/radio/send-message),
+
+```package
+radio-broadcast
+```

libs/radio-broadcast/docs/reference/radio/send-message.md

@@ -0,0 +1,43 @@
+# send Message
+
+Broadcast a coded message to other @boardname@s connected via ``radio``.
+
+```sig
+radio.sendMessage(0);
+```
+
+## Parameters
+
+* **msg**: a coded message.
+
+
+## Example: Broadcasting heart or skull
+
+Sends a ``heart`` message when ``A`` is pressed, ``skull`` when ``B`` is pressed. On the side, display heart or skull for the message.
+
+```blocks
+enum RadioMessage {
+    heart,
+    skull
+}
+input.onButtonPressed(Button.A, function () {
+    radio.sendMessage(RadioMessage.heart)
+})
+input.onButtonPressed(Button.B, function () {
+    radio.sendMessage(RadioMessage.skull)
+})
+radio.onReceivedMessage(RadioMessage.heart, function () {
+    basic.showIcon(IconNames.Heart)
+})
+radio.onReceivedMessage(RadioMessage.skull, function () {
+    basic.showIcon(IconNames.Skull)
+})
+```
+
+## See also
+
+[on received number](/reference/radio/on-received-number)
+
+```package
+radio-broadcast
+```