BLE mode by default (#1429)

* set open mode as default + pairing mode supported too

* remove comment

docs/projects/micro-chat.md

@@ -11,13 +11,9 @@ Use the **radio** to send and receive messages with other @boardname@.
 Use ``||input:on button pressed||`` to send a text message over radio with ``||radio:send string||``.
 Every @boardname@ nearby will receive this message.
 
-You can also add the ``||basic:show icon||`` and ``||basic:clear screen||`` blocks to show a simple animation when the message is sent.
-
 ```blocks
 input.onButtonPressed(Button.A, () => {
     radio.sendString("Yo");
-    basic.showIcon(IconNames.Chessboard)
-    basic.clearScreen();
 });
 ```
 
@@ -48,8 +44,6 @@ Press button **A** on the simulator, you will notice that a second @boardname@ a
 ```blocks
 input.onButtonPressed(Button.A, () => {
     radio.sendString("Yo");
-    basic.showIcon(IconNames.Chessboard)
-    basic.clearScreen();
 });
 radio.onReceivedString(function (receivedString) {
     basic.showString(receivedString);
@@ -65,9 +59,6 @@ If you two @boardname@s, download the program to each one. Press button **A** on
 Use the ``||radio:set group||`` block to assign a **group** number to your program. You will only receive messages from @boardname@s within the same group. Use this to avoid receiving messages from every @boardname@ that is transmitting.
 
 ```blocks
-/**
-* Pick a unique group in your classroom!
-*/
 radio.setGroup(123)
 ```
 

libs/core/pxt.json

@@ -57,9 +57,9 @@
                     "device_info_service": 1,
                     "eddystone_url": 1,
                     "eddystone_uid": 1,
-                    "open": 0,
+                    "open": 1,
                     "pairing_mode": 1,
-                    "whitelist": 1,
+                    "whitelist": 0,
                     "security_level": "SECURITY_MODE_ENCRYPTION_NO_MITM",
                     "partial_flashing": 1
                 }
@@ -67,26 +67,24 @@
         },
         "userConfigs": [
             {
-                "description": "No Pairing Required: Anyone can connect via Bluetooth.",
+                "description": "No Pairing Required (default): Anyone can connect via Bluetooth.",
                 "config": {
                     "microbit-dal": {
                         "bluetooth": {
-                            "open": 1,
-                            "pairing_mode": null,
-                            "whitelist": 0,
+                            "open": null,
+                            "whitelist": null,
                             "security_level": null
                         }
                     }
                 }
             },
             {
-                "description": "JustWorks pairing (default): Pairing is automatic once the pairing is initiated.",
+                "description": "JustWorks pairing: Pairing is automatic once the pairing is initiated.",
                 "config": {
                     "microbit-dal": {
                         "bluetooth": {
-                            "open": null,
-                            "pairing_mode": null,
-                            "whitelist": null,
+                            "open": 0,
+                            "whitelist": 1,
                             "security_level": null
                         }
                     }
@@ -98,7 +96,6 @@
                     "microbit-dal": {
                         "bluetooth": {
                             "open": 0,
-                            "pairing_mode": null,
                             "whitelist": 1,
                             "security_level": "SECURITY_MODE_ENCRYPTION_WITH_MITM"
                         }