TechPillar should use force_y_billboarding

[shino1]

I love XY billboarding (because it makes monsters look like 3D objects and not cardboard cutouts), but its pretty much only flaw is that "tech pillar" entity is so tall, it breaks it, and one appears as early as E1M1. I think everybody who uses XY would agree that making super-tall objects like tech pillar use "force y billboarding" would be an objective improvement.
Sure I can - and do - use a quick decorate patch, but not everybody knows how to use Slade, so this should be the default behaviour.