[patch] [cla] Slider/Spinner: Safari mousewheel support

[dante]

I've been playing around with mousewheel support and came up with a really nifty mousewheel listener to reliably give a positive or negative delta value. (actually in #6485, but this applies it to Slider)

It works w/ Safari 3, FF2/3, IE7 (from within macos/parallels, so need testing w/ "real" windows mouse), and Opera (though slider test locks up in opera 9, my demo using this techmo doesn't).

This is similar to #6485 in the shorthand and connections. I plan to go back and test spinner in Safari/Opera and supply new patch for that later.

[dante]

adds opera and safari mousewheel support to _spinner and slider

[bill]

Looks good to me.

[doughays]

(In [13739]) Fixes #6747 #6176. Committing patch from dante to add safari mouse wheel event handling.