Potion effects should never explode and always apply on self

Potions don't have a range. Like projectile enchantments, the effects should be applied regardless of the range in the ENAMstruct. Similarly, potions don't explode. Currently OpenMW spawns an explosion at 0,0,0 if the effect has an area.

The same should be checked for Constant Effect enchantments. Morrowind.exe does care about the Range of CE enchantments and doesn't apply Touch effects to the wearer. No explosions though.