1.3.10 - A few more critical bug fixed.

Burn bootloader was broken when BOD was enabled.
Wire.h had a bug in Wire.swap() that prevented it from compiling for most parts. Oops.
Comparator didn't compile - now it does, and there's a single codebase for this + megaTinyCore.

We also have CI running now, which didn't catch any major problems, but flagged a number of issues, now resolved, impacting library examples. Documentation and examples for EEPROM are improved, and code shared with megaTinyCore now. tinyNeoPixel works with millis disabled and comparator documentation is improved.