cleanup: remove obsolete code, make static, etc. Some rather trivial cleanup things like putting demo code into ifdefs, making functions static where possible, and against my normal policy of hard removing unused code, commenting it out at this point in time. Somehow, I think that this commented code might be useful in the near future as a new pressure sensor is coming. And finally, fixed some typo's in comment. Signed-off-by: Jan Mulder <jlmulder@xs4all.nl>