USBCON is definied by serial.h pullikng in MarlinConfig.h which in turn pulls in Arduino.h.  Defining in later includes has shown to cause compile issues so removing all extraneous calls for and potentially easier future linker troubleshooting.
more USBCON unification

・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

Some other pins formatting also

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

Remove unused ALARM_PIN from all the Configuration.h's

Keep "astyled" reformatting

* Updates the auto bed leveling comments ONLY.
* Renames "Z probe" word usage in //comments and #errors properly.

- `SD_DETECT_PIN` replaces `SDCARDDETECT`
- `SD_DETECT_INVERTED` replaces `SDCARDDETECTINVERTED`
- Revise the description of `SD_DETECT_INVERTED`
- Add a note about the override of `SD_DETECT_INVERTED` in
`Conditionals.h`

- Rename the pin so it can be tested with `PIN_EXISTS`
- Fix some incorrect tests for `SDCARDDETECT`

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

The instruction say to set a #define in fastio.h
However, that value is not included before this test.

Copied from jcrocholl's contributions to the OpenBeamUSA Marlin fork