Support delay in property transition

[#49843371]
Add atomTransition() to MD2D Scripting API

[#49843371]
Add new interactive presenting atomTransition()

[#49843371]

Note that this model is created completely by hand. Empty model is
used, as a fake properties set.

So, it's visible that we can easily support undefined / null model URL
(and then use just {} as model properties set).