[Suggestion] Add "Falling Sand" Entities (tested in 1.4.4-a4)

I just saw Xisumavoids latest video (https://www.youtube.com/watch?v=pQvOsOa0Vl8) on how to create vertical slabs. It uses the same techique that can be used to create half-slabs from gravity-blocks like sand or concrete-powder (just drop them on a cobblestone-wall).

I setup a small test and checked if Chunky would render them and it doesn't - which is perfectly fine and understandable as these "blocks" are entities as long as they are "falling".

But if its not a lot of work, this could be a nice addition as this "kinda bug" is actually useful.


(( And just to clarify: the concrete-powder thats visible in the chunky-render is additional concrete-powder I placed behind the falling blocks -> the falling blocks *are* missing ))

But its really not important - just a thought that crossed my mind after seeing the video.

Start by reproducing the reported setup from the issue: place falling sand or concrete-powder blocks on a cobblestone wall and render the scene in Chunky. Trace how the renderer handles falling block entities, then verify that these entities appear in the rendered result without losing the existing block rendering behavior.

Written by the indexing model from the issue text.