This change make the following commands correctly detect the 4B
however there may be an issue with reading GPIO inputs on the 4B
as they are always returning zero.

The aim of this change is to be the source-equivalent of the binary
package release 2.52[1] which was the last release before upstream
development ceased.

[1] http://wiringpi.com/wiringpi-updated-to-2-52-for-the-raspberry-pi-4b/

Sourced from http://archive.ubuntu.com/ubuntu/pool/universe/w/wiringpi/wiringpi_2.50.orig.tar.gz

Added gpio readall support for the Pi 0W.

Added fixed for a few minor things. pin driver for rht03/dht type
sensors. Network stuff is experimental - for now.

for kernels 4.8 onwards.

Some very old stuff might break.

Additional fixes for the ISR code and some tweaks here and
there. I've removed the checks for some operations that might
fail when using the gpiomem interface - which is now the default
way of doing things - if your program segfaults, then you
may need to use sudo on it.

Updating the GPIO command - new command - allreadall
ScrollPhat code
max31855 code (tested with adafruit breakout board)
more tests
updated rht03 code

Raspberry Pi v3 support.

Also affects the Pi v2 which also uses the new Revision
encoding scheme (It was slightly bodged before) This ought
to be relatively future proof, but who knows.

Fixed a minor thing in the examples Makefile
(not that anyone bothers to use it, judging by the emails I get )-:

Moved the extensions into wiringPi from gpio and made it more general purpose
more so that RTB and anything else can dymanically add devices
into wiringPi.
Changes to GPIO to updates for the SPI and I2C module loads
Added gpio unload for SPI and I2C.

Added a new way to setup SPI - by passing the mode in.

Support for the new Pi2 thing too

round at last..

Updated for the 0x0012 board revision on the new A+

of changing it for the B+)

Aded a gpio command: usbp hi/low - to change the usb power

to produce a nicer 'readall' output too.

It also understands new pins 53,54,55 and 56 in wiringPiSetupPhys()
mode to represent the pins on the P5 connector on the Rev 2 Pi's

Changes to pinMode() to allow new modes SOFT_PWM and SOFT_TONE.

bugfix in blink.sh - wring pin
improving the maxdetect routing - a little.
gpio pins

with wiringPiISR.
Added the ability to readall/reset from extension modules.
Changed the build script to use /bin/sh rather than /bin/bash as it seems
some installations don't have /bin/bash (or if they do, then the people who
are telling me that ./build gives them command not found are wrong)

Added the Quick 2 Wire codes, etc.
Minor typo/bug fixes.
Added more modules into gpio -x

one of the GPCLK drivers to generate a frequency up to
19.2MHz.

Tidied some code up and added the clock functions into the gpio
utility.

Added in generic 'blink' programs in the examples in C, RTB and Shell.
Updated wiringPi with a little big-file on the millis() function and
added in a new micros() function too.
Updated the examples with standard LGPL headers.
Added a new isr-osc.c test program - just for ISR timing purposes.

on non Raspbian systems (and even on some Raspbian systems it would appear ):

fixed a timing issue on softTone
fixed some issues in wiringPisetup introduced when optimising the mmap calls.

and developed the new ISR - Interrupt Service Routine
handler - much easier than the old waitForInterrupt code!

Minor tweaks to the gpio program to recognise the environment variable
WIRINGPI_DEBUG too, and removed the printing of the errors from the
main wiringPi setup routines (and added some new ones!)

delayMicrosecondsHard re-written - again.
Added a serialRead example program, and added in the okLed
to the examples too.
Updated/checked some of the GPIO/PWM code.
Added in some experimental servo and tone generating code and
and example or 2.
Tweaks to the gpio command to correctly load the I2C modules too.

allow access to the wiringPi to BCM_GPIO pin mapping tables.

Updated wiringPi to add new PWM controls.

General tidying up of some of the code round delayMicroseconds