multiple FWretract fixes

Previous version was broken by using G92 E0 between retract and recover.

Use C++ initialization list

 for volumetric E units

Move strings in ultralcd.cpp into language.h.

Conflicts:
	Marlin/language.h

Aragonese translation

Update language.h

Add/azteegx3pro

This reverts commit 6f76066a, reversing
changes made to e1ae7952.

Add Aragonese translation

Updated Polish translations.

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

Improved support for panelolu2 encoder and buzzer

Heater wattage reporting for M105 using EXTRUDER_WATTS and BED_WATTS

- Remove the two version of 16mHz. Crystal and resonator use the same
fuse setting. Also, Arduino IDE only showed the first one 16Mhz as a
board option.

- Added 20Mhz board option.

Symptoms for incorrect fuse setting:
- X axis move in one direction
- limit switches fail to trigger
- unable to reprogram the device via bootloader
- stops working when the reset switch is pressed.
- device fails to bootup when power by a slow raise power supply.

Solution:
- Disabled the jtag
- set the correct clock selection bit
- set the correct bootloader memory size
- enable brown-out setting
- enable clock power up delay

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

Change diameter code to 'D'