Add the ability to change player model size to under the normal height (maybe over by 1 block or so), to allow Pehkui size changes to be accurately represented.

Pehkui is definitly a mod we will look into (since immersive portals also uses it). But for now, we are looking into some other things.

pehkui works for the player's model, but the camera doesn't match the model's height.