Add the ability to set and get the wither invulunbility.

src/me/libraryaddict/disguise/disguisetypes/watchers/WitherWatcher.java

@@ -0,0 +1,28 @@
+package me.libraryaddict.disguise.disguisetypes.watchers;
+
+import me.libraryaddict.disguise.disguisetypes.Disguise;
+
+public class WitherWatcher extends LivingWatcher {
+
+    public WitherWatcher(Disguise disguise) {
+        super(disguise);
+    }
+
+    public int getInvul() {
+        return getInvulnerability();
+    }
+
+    public int getInvulnerability() {
+        return (Integer) getValue(20, 0);
+    }
+
+    public void setInvul(int invulnerability) {
+        setValue(20, invulnerability);
+    }
+
+    public void setInvulnerability(int invulnerability) {
+        setValue(20, invulnerability);
+        sendData(20);
+    }
+
+}