Unpickle an element even if it contains ContextEntity in its attributes
improve documentation

Add type synonyms: Username, Password, AuthZID, AuthData and Resource
merge branch '0.3.0.2-entityre_in_attr' of git://github.com/hiratara/pontarius-xmpp into hiratara-0.3.0.2-entityre_in_attr

Conflicts:
	source/Network/Xmpp/Stream.hs