Reworked pagination for better performance (at least in Lucene queries)
Some new sections, paragraphs and comments in User doc.
Set better style for decription in user documentation
Added NonRootObjectException in these operations in DataProvider:
 - getGraphByObjectId
 - getRelatedObjectsById
 - getPathById
 - mergeObjects
 - splitObject
 - getDocumentsContainingObjectById
 - getFilteredDocumentsContainingObjectById
Fixed save with joined objects
Added locking in service methods which modify db
Merge remote-tracking branch 'origin/server-impl'
Added logo in better quality and some info in About
Added all versions of logo
Merge?