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.

Added support for BQ ZUM Mega 3D board and stock Hephestos 2 thermistor.

because of hardware differences on the SERVO0_PIN

Keep "astyled" reformatting

Currently we use the probe exclusively as a device to find the build platform(bed).
For the currently supported setups this means, we use it as a additional min-endstop.
A triggered when not deployed probe disturbs the homing process for max-endstops.

Rename ENDSTOPPULLUP_ZPROBE to ENDSTOPPULLUP_ZMIN_PROBE
Rename Z_PROBE_ENDSTOP_INVERTING to Z_MIN_PROBE_ENDSTOP_INVERTING
Rename Z_PROBE_ENDSTOP to Z_MIN_PROBE_ENDSTOP
Rename DISABLE_Z_PROBE_ENDSTOP to DISABLE_Z_MIN_PROBE_ENDSTOP
Rename Z_PROBE_REPEATABILITY_TEST to Z_MIN_PROBE_REPEATABILITY_TEST
Rename Z_PROBE_ENDSTOP to Z_MIN_PROBE_ENDSTOP
Adjust comments accordingly
Remove Z_MAX  check for the probe in update_endstops().

Using an delta related idea of @clefranc from #61,
extended to the general change for all setups.

Tested with Prusa i3, max-z-endstop and permanently triggered z-probe.
Worked for @clefranc's delta.

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

to MELZI_MAKR3D.

Fix for #2288
As the normal MELZI also can have a 1284.

- Add 3 new lines to `pins.h` to remove 2 redundant tests in
`pins_RAMPS_13.h`

No way to fit Marlin into 32K.

Copied from jcrocholl's contributions to the OpenBeamUSA Marlin fork

Created a new board to make using RAMPS as a CNC machine controller
easier. It maps pin 8 to the spindle and pin 9 to the controller fan.

is not used.

be.
Added Sanity Check for it.
Added hook so it's enabled.

Typo fixes in comments in existing code.

- Patched up for most included configurations