Heretic-specific homing projectile, with the same weaknesses as the nitrogolem skull projectile.
Threshold and maxturn are integer values in angle dimensions.
No examples given.
A projectile running this codepointer will home into the target in Heretic style. Its angle difference to its target has to be smaller than threshold to home completely. Otherwise, it will only be able to spin by maxturn degrees. Also, homing vertically will only happen if the height difference is significant.