adding namespace to api categories (#330)

* adding namespace to api categories

* add icon for led

* adding icons for control, game, images, pins and serial.

libs/radio/radio.cpp

@@ -24,7 +24,7 @@ using namespace pxt;
 // payload: string length (9), string (10 ... 28)
 #define PACKET_TYPE_STRING 2
 
-//% color=270 weight=34
+//% color=270 weight=34 icon="\uf012"
 namespace radio {
 
     // -------------------------------------------------------------------------

libs/radio/radio.ts

@@ -1,7 +1,7 @@
 /**
  * Communicate data using radio packets
  */
-//% color=#E3008C weight=34
+//% color=#E3008C weight=34 icon="\uf012"
 namespace radio {
     export class Packet {
         /**

libs/radio/shims.d.ts

@@ -2,7 +2,7 @@
 
 
 
-    //% color=270 weight=34
+    //% color=270 weight=34 icon="\uf012"
 declare namespace radio {
 
     /**