Apply `ENABLED` / `DISABLED` macros to files needing only a small
number of changes.

- Apply standards to cardreader.*
- Fix minor issues with cardreader.cpp
- Apply standards to some other stale regions

Added boards.h which contains defines for all the board numbers, plus
some shorthand macros for less typing.

Added boards.h which contains defines for all the board numbers, plus
some shorthand macros for less typing.

Add digipot i2c control for MCP4451
Allow M907 to set i2c digipot currents in amps
Fix Makefile to allow Azteeg motherboards
Fix Makefile to allow Wire libraries only
Add beeper pin for Azteeg X3 Pro