Change disable/enable flags to booleans.

Minor ... 'improvement' to indicate that a bool really IS a bool and not an int (and make sure you can't set it to an unvalid value, such as <code>2</code> etc...

Backwards comparability is still maintained, because it accepts <code>Y</code> or <code>1</code> (as well as <code>N</code> or <code>0</code> respectivly).

Includes man update and a spelling error (srub should be scrub).