Common functions for all I/O pins.

Pins are normally created via IN or OUT so that their initial state is known. See IN.hpp and OUT.hpp

uint8_t GetBit(); // Get the bit mask for this Pin

bool IsValid(); // was this defined as a valid pin

// The following are only needed by devices which use the same I/O pin to change between in and out - eg some sonar devices

void SetInput(); // Change this into an input pin

void SetOutput(); // Change this into an output pin