- makes instrument knobs turn at a realistic rate
- removes redundant <min> and <max> specifications*
- corrects the indentation to reflect nesting depth
- corrects some descriptive names
* E.g. if the gyro compass heading is 365, there's no point clamping the
value to 360 before drawing it. Just using the given value is more
likely to be right - or, if it's wrong, at least we won't hide the bug.