fix for microsoft/pxt#396

pxtarget.json

@@ -79,15 +79,6 @@
         "aspectRatio": 1.22,
         "parts": true,
         "partsAspectRatio": 0.69,
-        "builtinParts": {
-            "accelerometer": true,
-            "buttonpair": true,
-            "ledmatrix": true,
-            "speaker": true,
-            "bluetooth": true,
-            "thermometer": true,
-            "compass": true
-        },
         "boardDefinition": {
             "visual": "microbit",
             "gpioPinBlocks": [
@@ -165,9 +156,13 @@
             ],
             "attachPowerOnRight": true,
             "onboardComponents": [
+                "accelerometer",
                 "buttonpair",
                 "ledmatrix",
-                "speaker"
+                "speaker",
+                "bluetooth",
+                "thermometer",
+                "compass"
             ],
             "useCrocClips": true,
             "marginWhenBreadboarding": [
@@ -330,4 +325,4 @@
         "userVoiceApiKey": "WEkkIGaj1WtJnSUF59iwaA",
         "userVoiceForumId": 402381
     }
-}
+}