Implement client-side spell counter for NPCs, fixes #345

Also makes all the continuous-spell-related methods in ISpellCaster default methods so they don't need implementing unless actually necessary.

src/main/java/electroblob/wizardry/entity/living/EntityEvilWizard.java

@@ -74,6 +74,7 @@ public class EntityEvilWizard extends EntityMob implements ISpellCaster, IEntity
 	// Field implementations
 	private List<Spell> spells = new ArrayList<Spell>(4);
 	private Spell continuousSpell;
+	private int spellCounter;
 
 	public EntityEvilWizard(World world){
 
@@ -175,6 +176,16 @@ public class EntityEvilWizard extends EntityMob implements ISpellCaster, IEntity
 	public Spell getContinuousSpell(){
 		return this.continuousSpell;
 	}
+
+	@Override
+	public void setSpellCounter(int count){
+		spellCounter = count;
+	}
+
+	@Override
+	public int getSpellCounter(){
+		return spellCounter;
+	}
 	
 	@Override
 	public int getAimingError(EnumDifficulty difficulty){