show only ledmap pixels, show bus lengths in segment visualization

index.js: segment visualization:
- max width if no pc
- don't show nr if only one segment
- Ledmap nr color depending on bus output

FX_2Dfcn.cpp / FX_fcn.cpp
- don't show ledmap -1 pixels

json.cpp: add busses.length to outputs

ws.cpp: peek back to strip.gPC only

wled00/json.cpp

@@ -771,6 +771,12 @@ void serializeInfo(JsonObject root)
     if ((ledMaps>>i) & 0x0001) ledmaps.add(i);
   }
 
+  //WLEDMM: add busses.length to outputs
+  JsonArray outputs = root.createNestedArray(F("outputs"));
+  for (int8_t b = 0; b < busses.getNumBusses(); b++) {
+    outputs.add(busses.getBus(b)->getLength());
+  }
+
   JsonObject wifi_info = root.createNestedObject("wifi");
   wifi_info[F("bssid")] = WiFi.BSSIDstr();
   int qrssi = WiFi.RSSI();