AR: trying to improve coexistence with HUB75

Hub75 is very memory hungry. So we try to make a bit more RAM available
* use 16bit samples when compiling with HUB75 support --> 3KB saved
* avoid using aPLL (HUB75 needs it)
* move audio buffers from BSS (always allocated) to heap (only allocated when FFTtask runs) --> 10Kb saved
* suspend live preview for 6 seconds when out-of-memory

wled00/ws.cpp

@@ -186,6 +186,12 @@ static bool sendLiveLedsWs(uint32_t wsClient)  // WLEDMM added "static"
   AsyncWebSocketClient * wsc = ws.client(wsClient);
   if (!wsc || wsc->queueLength() > 0) return false; //only send if queue free
 
+  #ifdef ARDUINO_ARCH_ESP32
+  static unsigned long ws_delay = 0;
+  if ((ws_delay > 0) && (millis() - ws_delay < 6000)) return false; // out of memory -> suspend for 6 seconds 
+  else ws_delay = 0;
+  #endif
+
   #ifdef ESP8266
     constexpr size_t MAX_LIVE_LEDS_WS = 256U;
   #else
@@ -223,6 +229,10 @@ static bool sendLiveLedsWs(uint32_t wsClient)  // WLEDMM added "static"
       last_err_time = millis();
     }
 	  errorFlag = ERR_LOW_WS_MEM;
+    #ifdef ARDUINO_ARCH_ESP32
+      ws_delay = millis(); // suspend for next 6 seconds
+      USER_PRINTLN("out of memory - live preview suspended for 6 seconds.");
+    #endif
 	  return false; //out of memory
   }
   uint8_t* buffer = reinterpret_cast<uint8_t*>(wsBuf.data());