Revision history for Perl extension WiringPi::API.

1.04    2016-08-22
        - implemented softPwmCreate(), softPwmWrite() and softPwmStop(), perl:
          soft_pwm_create(), soft_pwm_write(), soft_pwm_stop()
        - interrupts now work; added code to stop the erroneous extra call to
          the handler on first interrupt

1.03    2016-08-18
        - fixed call to SetupGpio(), case was wrong
        - renamed gpio_scheme() call to pin_scheme()
        - removed erroneous call to external module (pin_scheme())
        - POD cleanup, re-worded $pin descriptions, and fixed up setup*()
          routine explanations

1.02    2016-08-16
        - removed references to wiringPi pin numbering scheme being the default
        - added clarification in setup*() routine POD

1.00    2016-08-16
        - new export tags, :wiringPi exports the originally named wiringPi
          functions directly from XS. :perl exports the Perl representation
          of the functions, and :all exports them all
        - setup_sys() now exports all BCM pins with a system call with sudo,
          which alleviates the need to run as user root
        - interrupt code now implemented and working
        - renamed to WiringPi::API

0.06    2016-08-13
        - moved arg validation out of Core and into upper-layer client
          software. The idea is to keep this module as close to the C code
          as possible, so if this module is used directly, C will handle the
          problem
        - wrote custom physPinToWpi() C function, and added a phys_to_wpi()
          caller
        - we now shift off the object or class name if it is present in all
          sub calls
        - all parameter error handling out, and put it into the upper layers...
          we now pretty much call the C functions directly with little overhead

0.05    2016-08-11
        - added all of the wiringPiDev shared library LCD functions, and
          mapped them in ::Core

0.04    2016-08-10
        - wiringPiSetupPhys() has been implemented
        - added piBoardRev(), wpiPinToGpio(), physPinToGpio() and pwmSetRange()
          functions
        - added Perl->C mappings in POD

0.03    2016-08-10
        - added repo info to Makefile.PL
        - added get_alt(), maps to C getAlt(). This returns the current mode
          of a pin. Why it's not called getMode() is beyond me ;)

0.02    2016-08-10
        - added notices to POD
        - added POD for pwm_write()

0.01    2016-08-10
        - separated out from RPi::WiringPi
        - most core and system functions implemented