Implement Core.TickCount

Convert movement, actions (lift/use), combat, and spells to use Core.TickCount and avoid DateTime caveats (performance, system time dependency, etc)
Refactor DateTime.Now to DateTime.UtcNow
Add LOS check for Iron Maiden addon

Scripts/Items/Weapons/Abilities/DoubleStrike.cs

@@ -49,7 +49,7 @@ namespace Server.Items
 			{
 				BaseWeapon.InDoubleStrike = true;
 				attacker.RevealingAction();
-				attacker.NextCombatTime = DateTime.Now + weapon.OnSwing( attacker, defender );
+				attacker.NextCombatTime = Core.TickCount + weapon.OnSwing(attacker, defender).TotalMilliseconds;
 				BaseWeapon.InDoubleStrike = false;
 			}
 		}