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.

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

Apply `ENABLED` / `DISABLED` / `HAS_SERVOS` macros to pins files.

There’s no need to ask users to uncomment Max Endstop pins when they
have them. These will be set to -1 later if the endstop option is
disabled.

Hopefully this is helpful to organization and future expansion….

There’s no need to ask users to uncomment Max Endstop pins when they
have them. These will be set to -1 later if the endstop option is
disabled.

Hopefully this is helpful to organization and future expansion….

There’s no need to ask users to uncomment Max Endstop pins when they
have them. These will be set to -1 later if the endstop option is
disabled.

Hopefully this is helpful to organization and future expansion….