ESP32 compatibility in Arduino.

Hello Camilo Parra Palacio, as you might have noticed, I'm trying to use my Ottoky as a standard Otto, I'm starting with Arduino IDE first, and I guess compatibility in OttoBlockly will be easier after that.

I can now run the "Otto_allmoves" example, but I had to fix the following problems. Please tell me if you need more explanations/details, or if you need me to commit fixes somewhere.
1) softwareserial library included is not compatible with ESP32, I made a quick, temporary fix by adding #define SERIALCOMMAND_HARDWAREONLY in the sketch
2) servo library is not compatible with ESP32. For this one no quick fix, I used ESP32Servo.h library which has the same syntax, and put a #ifdef statement to select library for ESP32 or "standard arduino" in Otto9.h, Oscillator.h, Oscillator.cpp, Otto9Humanoid.h
#ifdef ARDUINO_ARCH_ESP32
#include <ESP32Servo.h>
#else
#include <Servo.h>
#endif

3) Oscillator.h and .cpp use a lot of _[uppercase stuff] variables, these are reserved and should not be used as variable names. Not a problem in basic arduino but it matches the names of some macros in ESP32, so they must all be renamed: _TS => _ts, _A => _amp etc etc

4) min(...) macro used in TimerFreeTone is not defined in ESP32 code, so I added it in TimerFreeTone.h after the include of Arduino.h. There should be a better place to define this or fix this problem, but I don't know where/how yet...

#ifndef min
#define min(a,b) (((a) < (b)) ? (a) : (b))
#endif