Not Using Scroll Wheel Fix

[deram_scholzara]

I don't have an axis set up for the mouse scroll wheel because I don't use it in my game.  NGUI, however, currently expects that if you're using the mouse, you must be using the scroll wheel.  To get around this, I changed this part of UICamera.cs:

1.                         float scroll = Input.GetAxis(scrollAxisName);
2.                         if (scroll != 0f) Notify(mHover, "OnScroll", scroll);

to this:

1.                         if (!string.IsNullOrEmpty(scrollAxisName)) {
2.                                 float scroll = Input.GetAxis(scrollAxisName);
3.                                 if (scroll != 0f) Notify(mHover, "OnScroll", scroll);
4.                         }

[ArenMook]

That makes sense. I'll mirror the change on my end.