Scrollwheel variables

[Skyld]

I have two suggestions for scrollwheels.

- GuiScrollCtrls and such should be able to side-scroll when the text does not wrap. Currently if there are no scroll bars visible, then it is not possible to scroll left and right unless you select and drag across the text.
- The addition of a scrollwheelydelta variable for reading side-scrolling so that it is possible to see whether the side-scrolling is being used by those who have the capability.