Is there an Arduino library, for ESP with at commands ?

Hardware Arduino Zero
11

This exactly my change.

Changed on RingBuffer.cpp & RingBuffer.h & EspDrv.cpp & EspDrv.h & Scketh
RingBuff Class on RingBuffW
Added on EspDrv.cpp
#include <stdarg.h>
Changed on EspDrv.cpp
vsnprintf_P (cmdBuf, CMD_BUFFER_SIZE, (char*)cmd, args);
with
vsnprintf (cmdBuf, CMD_BUFFER_SIZE, (char*)cmd, args);

But unit reboot each fiew seconds.
ESP led, blink repeatedly every few seconds, USB driver disappears and Returns.