More correct checking for having subtypes (card.hasSubtype()). Changeling ability. Refactored all cards.

Mage/src/mage/game/stack/Spell.java

@@ -206,6 +206,11 @@ public class Spell<T extends Spell<T>> implements StackObject, Card {
 		return card.getSubtype();
 	}
 
+	@Override
+	public boolean hasSubtype(String subtype) {
+		return card.hasSubtype(subtype);
+	}
+
 	@Override
 	public List<String> getSupertype() {
 		return card.getSupertype();