* Get UBL Mesh Generation, Mesh Save & Mesh Load working with 32-Bit platforms

* clean up read_data() and write_data() for non-LPC1768 HAL's

* Get read_data() and write_data() return codes consistent

All HAL's read_data() and write_data() return false if they succeed.

* Get read_data() and write_data() return codes to be consistent

Make read_data() and write_data() return true if an error happens.

* Say UBL is now checked out on machine types in default Configuration.h file.

Replace ARDUINO_ARCH_AVR with __AVR__ to better detect architecture for non-Arduino dev environments.  Resolves compile failure in PIO for 8-bit Teensduino targets

More info:
https://forum.pjrc.com/threads/33234-Using-Teensyduino-Selecting-Teensy-3-2-3-1-board-has-incorrect-platform-define
http://www.atmel.com/webdoc/avrlibcreferencemanual/using_tools_1using_avr_gcc_mach_opt.html

Implement AVR Platform