- Clean up the API to use a `static` class instance to adhere to Marlin convention
- Add `const` position data access for read/write
- Add Storage capacity to the interface

* 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.

Implement AVR Platform