* bugfix: correct order of setting `DDRn` and `PORTn`
* optimisation: `enum` and `static const` instead of macros
* optimisation: `PT6302_startup` is now `inline`
* optimisation: functions are now static
* bugfix: `data` is now rotated and stored instead of just rotating
* special thanks to @kissadamfkut for pointing all of this out to me