Usage
Commands - one of:
	./new-gpiotest set-input <pin>
		Sets pin to be an input pin
	./new-gpiotest set-output <pin>
		Sets pin to be an output pin
	./new-gpiotest get-direction <pin>
		Gets and returns pin direction
	./new-gpiotest read <pin>
		Gets and returns input pin value
	./new-gpiotest set <pin> <val>
		Sets output pin value
	./new-gpiotest pwm <pin> <freq> <duty>
		Starts PWM output on pin
	./new-gpiotest pwmstop <pin>
		Stops PWM output on pin
	./new-gpiotest irq <pin> <irqtype> <irqcmd> <debounce>
		Enables IRQ handling on pin
	./new-gpiotest irqstop <pin>
		Terminates IRQ handling on pin
	./new-gpiotest expled <ledhex>
		Starts output to expansion led
	./new-gpiotest expledstop
		Terminates output to expansion led
	./new-gpiotest info <pin>
		Displays information on pin(s)
	./new-gpiotest help
		Displays this help information
Where:
	<pin> is one of
		0, 1, 6, 7, 8, 12, 13, 14, 15, 16, 17, 18, 19, 23, 26, all
		A <pin> of all can only be used for:
			info, set-input, set-output, set
	<val> is only required for set:
		<val> is 0 or 1
	<freq> is PWM frequency in Hz > 0
	<duty> is PWM duty cycle % in range 0 to 100
	<irqtype> is the type for IRQ and is one of:
		falling, rising, both
	<irqcmd> is the shell command to be executed when the IRQ occurs
		Must be enclosed in " characters if it contains
		spaces or other special characters
		If it starts with the string [debug],
		debug output is displayed first
	<debounce> is optional debounce time for IRQ in milliseconds
		Defaults to 0 if not supplied
	<ledhex> specifies the hex value to be output to expansion led
		Must be a six digit hexadecimal vale with or without leading 0x
		The order of the hex digits is: rrggbb