Offer a less verbose approach to adding tweens to a Timeline

[WesWedding]

Nothing is explicitly wrong with timeline.add(*TweenDuino::Tween::to(brightness,50UL, 255.0));
but it's super verbose but all the namespace/scoping junk is confusing to a novice coder.

timeline.addTo(brightness, 255.0, 50) is a lot clearer. We're adding a tween to of the "brightness" variable to 55.0 that will take 50 milliseconds. It's a line half as long, without someone needing to understand what all that TweenDuino::Tween stuff is or telling someone to add using namespace TweenDuino to their files just to use our lib.

[WesWedding]

Why not just remove the reference from each add() call, too? Set the reference in the constructor and just make things even more simple with timeline.addTo(255.0, 50)