I was made aware some time ago that flat sprites did not have the same rotation code as models, which is supposedly the appropriate manner of doing so. This PR will bring it in line with the model rotation code and behave just like it. However, any mods reliant on the old behavior will inevitably be forced to update their code as it's no longer representing the current means of rotation.
As such I'm expecting to get flak for this. Probably a lot.
Attached is a demonstration file. Use "give z" in console and two sprites will spawn, featuring a sprite on a flat model plane (left) and a flat sprite (right).
The current implementation means users can avoid using quaternions or whatever else is there to keep the angle and pitch consistent, but the PR will ensure consistency so those who use models don't need a separate condition.
Personally, I'm torn directly down the middle if I want this or not, so I've marked the PR as draft so we can have a calm and civil discussion about it.
