[AttenuatedTweenProperty] Added a AttenuatedShakeTweenProperty and AttenuatedOscillateTweenProperty

[jpsarda]

[edit] I've pushed another commit to create a more generic AttenuatedTweenProperty that can be used for shaking, but also oscillating, and maybe other things. I tested for oscillateFloatProp, shakeFloatProp, oscillateColorProp and shakeColorProp and it works really well.

original description :

Added corresponding entries in GoTweenConfig ( shakeFloatProp, intFloatProp, etc…).

This is a quite elegant way to add a lot of shake options with only one new tween property class. I have the feeling that referencing a tween property inside another tween property opens the way to a new range of powerful tween properties, but not sure yet exactly how this can be exploited and for what precise goal.

Note that I've tested only the shakeFloatProp(...) method but I don't see why other methods wouldn't work.

Hope you accept this, because for example in a 2D engine like Futile, we can't use the current shake tween property that request a Transform for the target.