[2.2.12 PR1] All SPR2 Sprites Draw Models

GoalRing is using SPR2_GEND to draw custom goalring sprites, but I believe some kind of change to how models draw with sign sprites caused seemingly all SPR2_* sprites, including custom ones, to be drawn as models. Not sure if we could have some sort of a flag or a Lua addition, like a player.mo.sprite2model boolean for example.