Game server/skill system: cleaned up non-durational type 3 spells.
 * Magic hammer now repairs weapons as well.
 * Implemented support for DirectType 5 (adjusts target's HP by a percentage); resolves #358.
 * Implemented support for DirectType 8 (HP absorption not limited to players).
 * Implemented support for DirectType 11 (true damage to a target)
 * Implemented support for DirectType 13 (chance to reduce target's armour/weapon durability).