1.3.0 - Board manager improvements, enable/disable millis, new tinyNeoPixel library

This release adds two exciting new features - a menu option to enable/disable the millis/micros timer (in order to save flash), and a new highly integrated tinyNeoPixel library that supports all clock speeds from 7.3728MHz and up. See the documentation ( https://github.com/SpenceKonde/ATTinyCore/blob/master/avr/extras/tinyNeoPixel.md ) for details.
This release also corrects a few issues:
digitalPinToInterrupt for INT0 on 841/441 was still not correctly fixed in 1.2.5; now it is.
Correct issue with slave mode on chips with slave-only hardware I2C.
Board Manager: Ensure that the latest AVRDude version (6.3.0 arduino17) is installed, this fixes compatibility problems depending on other installed cores
Board Manager: Ensure that avrgcc 7.3.0 is installed, this will, among other things, fix compatibility issues with Mac OS Catalina.