Creality board is a Melzi / Sanguinololu variant, but using different pins for LCD control (and maybe other minor variations)

Add support for new electronics
www.reprapobchod.cz

SCK_PIN can't be defined as DIO[number] they mus be defined as pure number.
So rebuilding the structure of fastio.h in pins.h.

Replace all fastDigitalRead/Write() with READ/WRITE()

Define SCK_PIN, MISO_PIN, MOSI_PIN in pins.h if not already defined in the pins_*.h files.

Remove these conditional pin definitions from the pin-files. They are now always defined.

Define separate sets of SPI-pins for AT90USB with and without Teensy support in fastio.h.
Likely this was the main reason for all that confusion about the AT90USB-SPI pins.

Supports both dual and single head printers (with the correct config).
Includes community sourced feed rate fix.

Rename / move files.

Remove redundant definitions.

Following up on #3231

The PrintrBoard Rev F utilizes a mcp4728 DAC to set motor current. Printrbot's implementation utilizes 2 new M-codes to set and write the DAC settings to the DAC EEPROM: `M909` (Read DAC) and `M910` (Write DAC). `M907` is re-used to set value, `M908` for direct control.

The Pins file for the RevF board is included.