Merge pull request #316 from Eridia/master

Game Server/skill system: "Summon friend" should not be allowing the caster as the target.
Game server/skill system: minor amendment to last commit to ensure it sends the fail packet instead.
Game server/skill system: type 5 (cure/resurrection-like skills) now support groups. Resolves #315.
Game Server/Skill system : MagicAttackAmount Minor bug fix