[Request] backport dota 2 pre-reborn's cloth simulation

[TotallyARussian]

dota 2, the source 1 version, before the reborn update that ported it to source 2 had cloth simulation, among other things, i think it'd be great to have it, some extra documentation on it would be nice too, not sure realistic this request is, sorry.

[kumfc]

There's many cool things on later branches of source engine. It's unlikely they will ever be backported, it's easier to port TF2 the other way.