Added wait() method to delay movement at the specified point

[klapstoelpiloot]

This implements my request #29

[mobius3]

Thanks! I see the point of having a wait() feature. There are a couple things that needs to be addressed in your PR:

• your indentation looks off in regard to the rest of the project (it may be that the indentation of the project looks off in regard to the rest of the world but it is what it is :)
• I se that you've made the calculateTotal() function. Since it's not returning a calculation but rather updating totals, I believe updateStackedTotals() would be a better name orsomething else that implies change
• I'd implement wait() using tween::during() instead of duplicating it's code. I'd also say to call to() before, with the last value, but unboxing it may be somewhat hard to do so (see tween::dispatch(), not pretty). But for the duration, calling tween::during() is the way to go. And maybe we don't actually need the calculateTotal/updateStackedtotals function anymore.
• I believe you should set the stepped easing for this. By default tweeny it uses linear easing which makes unecessary calculations in this case. stepped returns always the first value which is what you want here.
• You should explain in the docs of this function that it is effectively equal to calling (from(a).to(a).during(...).via(stepped)) because although we're providing a useful functionality, we're also breaking user expectations in regards to the amount of easing points. It is known that to() adds a point but that wait() adds another is not and it's not obvious and this breaks seek() and jump() expectations. This has to be made explicit.

Thanks again for your PR!

[klapstoelpiloot]

Fair points. I'll see what I can do to implement your requested changes.