Game server/skill system: implemented support for weapon enchant & armor enchant scrolls (armor enchant wasn't handled correctly); refs #229.
Game server/skill system: implemented support for death taunt (skills); resolves #356.
Game server/skill system: minor tweak to remove duplicate canUseSkills() check.
Game server/skill system: reimplemented the generic CanAttack() check in UserCanCast() (wanted to remove it as IsAvailable() checks that, but it all needs to be cleaned up a bit first -- better to keep things behaving the same for now).
Game server/skill system: removed potential extra compensation ticks of HOT/DOT skills, as the expiration time on the client is desynced, causing a little confusion.