New compile time opiton for alternative 'prompt' debounce algorithm.
Button state changes are avaliable imideatley, so long as the previous
state has been stable for the timeout period. Otherwise the state will
be updated when the timeout period allows.
- Able to report acurate switch times normally with no delay.
- Compatable with exising usage.
- Use when prompt switch transition timing is important.
ChrisGallagher