In the Arduino IDE, boolean is an alias for bool. The Arduino IDE might deprecate boolean in the future. See https://github.com/arduino/Arduino/issues/4673 for details. Command: find drivers -type f | xargs sed -i 's/boolean/bool/g'
The rules are in .tools/astyle/config/style.cfg and can also be reviewed at https://www.mysensors.org/view/260#coding-guidelines-core-library