Demo programs:
blinken-lights-c.c		Original program
blinken-lights.cc		Original program, but for C++ compiler
blinken-lights2.cc		ledCycle as template function
blinken-lights2-c.c		ledCycle as macro
blinken-lights3.cc		ledHalfCycle template
blinken-lights4.cc		ledHalfCycle template with on/off template parameter
blinken-lights5.cc		delay_ms using constexpr
blinken-lights6.cc		delay_ms as library function
blinken-lights7.cc		initial GpioOut class version
blinken-lights8.cc		led as local variable in main
blinken-lights9.cc		GpioOut as template
