Inconsistency: Blackstone cannot be placed sideways

20w19a changes blackstone blocks so that they use the top texture on the bottom face as well, bringing them more in line with their sister basalt block. However, unlike basalt, they cannot be placed directionally across all three axes.

Not sure if this counts as a feature request as the two blocks are rather closely related and other blocks which are pillar-shaped like it tend to have directional placement.