lwip lib bundled with esp32 Arduino supports only one ntp server. Any additional servers set are just silently ignored.
This default is different from esp8266 Arduino core and very confusing. Most of the examples provided uses 3 different ntp servers for redundancy while only the first one is used actually.
Addressing issue #4964
* TX Flow Control and Code cleanup
* Use semaphore instead of delay
TX functionality is done.
* Use single buffer and empty queue on exit
* Fix compile issues because of LwIP code relocation
* Add temporary header to fix Azure not compiling
* Fix AsyncUDP early init
* AsyncUDP Multicast fixes
* Add source mac address and rework multicast
* Allow redefinition of default pins for Serials 1 and 2
* Update IDF to 3276a13
* Update esptool.py to 2.5.0
* Fix sketches
* Fix log level in BluetoothSetial
example:
```cpp
//done once on WiFi init
configTime(-7200, 3600, "pool.ntp.org");
//get local time
struct tm timeinfo;
if(!getLocalTime(&timeinfo)){
Serial.println("Failed to obtain time");
return;
}
//print time
Serial.println(&timeinfo);
//print time with different format
Serial.println(&timeinfo, "%A, %B %d %Y %H:%M:%S");
```
fixes: https://github.com/espressif/arduino-esp32/issues/29
