1.4.0

• New board manifests for the following generic MCUs: ATtiny1604, ATtiny1606, ATtiny1607, ATtiny1614, ATtiny1616, ATtiny1617, ATtiny202, ATtiny204, ATtiny212, ATtiny214, ATtiny3216, ATtiny3217, ATtiny402, ATtiny404, ATtiny406, ATtiny412, ATtiny414, ATtiny416, ATtiny417, ATtiny804, ATmega64, ATtiny806, ATtiny817
• Initial support for megaTinyCore
• Updated megaAVR Arduino core to v1.8.7 (release notes)
• Updated MegaCoreX to v1.0.7 (release notes)
• Improvements to fuses and bootloader programming process
• Minor fixes and improvements (#14, #15)