This simplifies code as there is no longer a distinction between
"normal" providers and introspection providers in ProviderManager
necessary.
It's also easier to get an idea where introspection is used for parsing.
this is the first stop towards fixing "SMACK-65: parsing should look for
depth", by providing the initial parsing depth to the provider. Some
methods (.e.g parseMessage) now use the depth as abort condition,
instead of a unclean String equals check.
parseIQ() and parseExtension() where both renamed to parse.
This also restricts the Exceptions thrown by the parse method, to just
XmlPullParserException, IOException and SmackException (not really a big
victory, but nevertheless a slight improvement).
StreamFeatureProvider is now gone, we simply use PacketExtensionProvider
for stream features.
Florian Schmaus