fix(core): Adds Hashed & Hierarchical Timer Wheel (#655)

- Removes TimerPriority
- Removes TimerThread
- Adds a [Hashed & Hierarchical Timer Wheel](http://www.cs.columbia.edu/~nahum/w6998/papers/ton97-timing-wheels.pdf)

Projects/UOContent/Spells/Base/Spell.cs

@@ -860,8 +860,6 @@ namespace Server.Spells
             public AnimTimer(Spell spell, int count) : base(TimeSpan.Zero, AnimateDelay, count)
             {
                 m_Spell = spell;
-
-                Priority = TimerPriority.FiftyMS;
             }
 
             protected override void OnTick()
@@ -898,8 +896,6 @@ namespace Server.Spells
             public CastTimer(Spell spell, TimeSpan castDelay) : base(castDelay)
             {
                 m_Spell = spell;
-
-                Priority = TimerPriority.TwentyFiveMS;
             }
 
             protected override void OnTick()