* Fixed a bug in the X11 handling of scrollwheel/mouse. The old code,

 * Fixed a bug in the X11 handling of scrollwheel/mouse.  The old code,
   I believe, checked if *either* a wheel or button callback was set,
   and then decided which to use---and unconditionally called it.
   I left the "either" check in, but added additional checks before
   actually doing the invocation.
 * Lots of reformatting.  Massive.  The usual suspects, though, and fairly
   trivial: Re-indenting to standard size, shuffling some spaces to match
   the freeglut "standard" of:
     if( ... )
   ...and:
     func( ... )

git-svn-id: svn+ssh://svn.code.sf.net/p/freeglut/code/trunk/freeglut/freeglut@285 7f0cb862-5218-0410-a997-914c9d46530a