Allow user to specify desired behavior for out-of-bounds touches

[kiwistrongis]

Currently, out-of-bounds touches are clamped into their touch-source's bounds, but Mark and Chris have previously mentioned that they think out of bounds touches should be effectively ignored.

Both are valid behaviors. Personally, I prefer the former - It's easier, simpler, and more informative. ( plus I've already implemented it ;P )

Here are few possible behaviors:

• active, clamp to bounds
• active, scaled by distance from bounds
• inactive, not drawn in any way
• inactive, drawn clamped to bounds
• inactive, drawn clamped to bounds, scaled by distance from bounds