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

I added #define for LCD_FEEDBACK_FREQUENCY_HZ and
LCD_FEEDBACK_FREQUENCY_DURATION_MS  which is used to alter the default
buzzer sound.

When selecting Panelolu2 in configuration.h:
- it automatically sets the correct ENCODER_PULSES_PER_STEP and
ENCODER_STEPS_PER_MENU_ITEM.
- if LCD_USE_I2C_BUZZER is defined it will also set the default
LCD_FEEDBACK_FREQUENCY_HZ and LCD_FEEDBACK_FREQUENCY_DURATION_MS

When selecting the sanguinololu 1284p the following is true:
- its now enables  LARGE_FLASH
- It enables the gcode M300 when the panelolu2 LCD_USE_I2C_BUZZER is
defined

This reverts commit b7eadb9f37.

I tested this and it works.

Included support for BT dongle on AT90USB boards.
Added LCD Shift Register LCD control
Included support for RepRap Clone Wars project board (SAV MKI).

Hopefully fixed viky button handling without braking other boards

Include Pins cpu Sethi 3D

Diffed and merged, preserving my updates

Integrated fixes from henrikbrixandersen pull request #504

merged from code downloaded from reprapworld.com

- changed the variables from keypad to reprapworld_keypad
- added a missing ifdef check

Also cosmetic comment changes and spelling corrections in printed
messages

The LARGE_FLASH flag allows superfluous features to be excluded
on boards with less memory

These definition contain also the definition for the graphics LCD.

The motherboard 35 is a config without bed with this pins setting :
D8 Extruder
D9 Fan
D10 Controller Fan

These definition contain also the definition for the graphics LCD.

This includes refactoring the buttons code to remove a large amount of
non-pin dependent duplication from pins.h.