raspberrypi-ua-netinst v1.2.1

Changelog:

• added compatibility for onboard wireless lan with model 3B to get used by installer and system (no ethernet needed)
• added more configuration variables
  • allow user to access GPIOs
  • create/add user to (system) groups
  • permit/prevent root remote SSH login
  • ...
• accelerated boot when using custom network connection
• added serial console for model 3B
• added universal installer output to serial
• fix installation error handling
• minor fixes and improvements (output cleanup, code cleanup)
• improved quiet boot
• removed initramfs duality

Bugfixes:

• v1.2.0 build failed if git version had no tag