Improve privacy parsing and API. Add NumberUtil

Make 'order' an long

Parse fall-through case's child elements (message, iq, presence-in,
presence-out)

Remove

privacy.addExtension(new DefaultPacketExtension(parser.getName(), parser.getNamespace()));

at the beginning of PrivacyProvider. Was there since day one for an
unknown reason.

smack-core/src/main/java/org/jivesoftware/smack/util/NumberUtil.java

@@ -0,0 +1,34 @@
+/**
+ *
+ * Copyright © 2015 Florian Schmaus
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.jivesoftware.smack.util;
+
+public class NumberUtil {
+
+    /**
+     * Checks if the given long is within the range of an unsigned 32-bit integer, the XML type "xs:unsignedInt".
+     *
+     * @param value
+     */
+    public static void checkIfInUInt32Range(long value) {
+        if (value < 0) {
+            throw new IllegalArgumentException("unsigned 32-bit integers can't be negative");
+        }
+        if (value > ((1L << 32) - 1)) {
+            throw new IllegalArgumentException("unsigned 32-bit integers can't be greater then 2^32 - 1");
+        }
+    }
+}