Devel giga

[travis-farmer]

herein i resubmit my first pull-request for my port to the Arduino Giga board.
the following library is needed to compile:
https://github.com/arduino-libraries/Arduino_AdvancedAnalog
it is a mainstream library, and i don't anticipate a future conflict.

I have built for UNO, Mega2560, Giga, Nano, and ESP32. the last two failed. Nano because of size requirements for firmware (i don't know what settings it is supposed to have), and the ESP32, again, because i don't know what settings it is supposed to have.

i have tested...
I2C: PASSED
Current sensing: PASSED
DCC Signal: PASSED
WiFi: PASSED (with esp wifi, NOT the giga WiFi)
Ethernet: PASSED
USB Serial: PASSED
JMRI Connection (serial/wifi/ethernet): PASSED
ED Connection (wifi/ethernet): PASSED

DCC Function: loco moves and functions work. reading and writing CV work.
if i have missed something, you know how to reach me.
the IO_CMRI.h and IO_CMRI.cpp i got from Ash got included... sorry about that. He has stated to me they are fine to include in the devel branch. they were unchanged by me.

[travis-farmer]

removed Ash's CMRI from my fork

[travis-farmer]

#define GIGA_EXT_EEPROM
that line in the config.h will enable EEPROM if the EEPROM module is attached to I2C.

[travis-farmer]

on Giga ONLY, add or leave out #define GIGA_I2C_1 to choose Wire1 or Wire, respectfully.
this way the user can choose if Wire (pins 20 and 21) is used, or Wire1 (pins by the AREF pin) is used. i think the third I2C, pins 8 and 9, should be avoided in that the motor driver may use them, and they do not come factory with I2C pull-up resistors.