ISPN-3636 Chapters in the "Getting Started Guide" not delimited properly

Append an empty line at the end of the chapter files included before these chapters to fix the formatting issue.
ISPN-3032 Allow use of multiple classloaders for finding parser services (fixes problems with modular classloaders)
ISPN-3639 PFER calls in INVALIDATION caches should be visible locally
ISPN-3597 ClusterRegistry should provide event notifications

* Add methods addListener, removeListener
* Also add containsKey convenience method
Refactor ProtobufMetadataManager to use ClusterRegistry
Move method ProtobufMetadataManager.readStream to commons Util
ISPN-2143 Improve how different indexed caches sync up on new indexed types

* The known classes are no longer kept in a map in QueryInterceptor. They are added in the ClusterRegistry instead (in a unique scope per cache) so the information is automatically disseminated in the cluster.
* As a consequence, IndexUpdateCommand does not need to propagate the known classes info, this is already taken care of.
* QueryInterceptor.getKnownclasses method is removed as it's no longer needed
ISPN-3651 Allow @Listener classes to be non-public

It's better not to impose such a restriction.