PacketExtension.from(Packet), deprecate getFrom()

add 'from(Packet)' to DataForm

documentation/developer/stanzas.md

@@ -0,0 +1,25 @@
+Developer Documentation: Stanzas and PacketExtensions
+
+PacketExtension
+===============
+
+The static `from(Packet)` Method
+--------------------------------
+
+Every PacketExtension class must have a static `from()` method that retrieves that extension for a given Stanza (if any).
+
+Sample Code
+
+```java
+public static RSMSet from(Packet) {
+  return packet.getExtension(ELEMENT, NAMESPACE);
+}
+```
+
+Sometimes certain PacketExtension's are only found in one stanza type, in that case, specify the parameter type. For example `public static CarbonExtension getFrom(Message)`.
+
+
+
+
+
+