Creates a keep upright constraint.
This function only works on prop_physics or prop_ragdoll.
1 Entity ent
The entity to keep upright
2 Angle ang
The angle defined as "upright"
3 number bone
The bone of the entity to constrain (0 for boneless)
4 number angularLimit
Basically, the strength of the constraint
The created constraint, if any or false if the constraint failed to set