Removed some extraneous whitespace.

Removed some extraneous whitespace.
Changed YES/NO to true/false; do not confuse BOOL (Objective-C) with bool (C++).
Changed some of the indentation to match that the rest of wxCocoa.

There was an if (isLastSoundInScope = NO) which I think was wrong not only
because it used NO rather than false but also because it's an assignment
rather than a test.  Changed it to if (!isLastSoundInScope).

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@29972 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775