Convert hibernate3_5 back to plugin project
replace uses of org.hibernate.mapping.PersistentClass by org.jboss.tools.hibernate.spi.IPersistentClass
fix failing tests
fix failing HbmExporterTest
fix failing OrmDiagramTest
more fixing of failing tests
remove uses of org.hibernate.mapping.SingleTableSubclass and org.hibernate.mapping.JoinedSubclass
remove trailing occurrences of org.hibernate.mapping.JoinedSubclass
move SpecialRootClass to package org.jboss.tools.hibernate.legacy in the org.hibernate.eclipse plugin
remove occurences of org.jboss.tools.hibernate.legacy.SpecialRootClass