Introducing Smack's own XmlPullParser interface which tries to stay as
compatible as possible to XPP3. The interface is used to either wrap
StAX's XMLStreamReader if Smack is used on Java SE, and XPP3's
XmlPullParser if Smack is used on on Android.
Fixes SMACK-591.
Also introduce JUnit 5 and non-strict javadoc projects.
This adds supports for an experimental protocol flow where a pending
friend request's decission is later on deliverd to the requestor after
the owner made its decission.
Florian Schmaus