Enabling connect properties on double slabs

[lvinc71]

Optifine's CTM specification clearly does not support "transparent" (non full) blocks, which is understandable.
But there are blocks that are considered "transparent" even if they are visually full blocks : double slabs.

I was trying to figure out how to change the textures of a double smooth stone slab when placed above a certain block, but connectBlocks and connectDirections do not seem to work with double slabs, which I think would not really break anything.

Do you think enabling these properties on double slabs may be doable ?

[PepperCode1]

connectDirections doesn't exist and never existed, as far as I know. connectBlocks only works for method=overlay. Enabling it for other methods is tracked in #481. Allowing overlays to be applied on non-full blocks is tracked in #421. However, double slabs are not transparent blocks and should work the same as any other full solid block for the purposes of CTM.