This allows the use of D4 as PS_ON since MKS Gen doesn't have a PS_ON pin. However this effectively allows only 3 servos (instead of 4).

Signed-off-by: Alexey Shvetsov <alexxy@gentoo.org>

・More ANALOG NUMBERING to Analog Input
・Add comment header to all the section of all the pins files

・Sort sections as follows:
1. Some special definitions (USBCON, LARGE_FLASH, etc)
2. Servos
3. Limit Switches
4. Z Probe
5. Steppers
6. Temperature Sensors
7. Heaters / Fans
8. Misc. Functions
9. LCD / Controller

・Move MAX6675_SS into "Temperature Sensors" section
・Adjust spacing

Includes:
  *firmware version / branch / date.
  *extruder count
  *board information (name, serial details, power supply type)
  *thermistors (names, min/max temperatures)
  *printer statistics (PRINTCOUNTER details)

Thanks to @thinkyhead for contributions.

Following up on #3231

- Patched up for most included configurations

- Also apply cleanup for #1514