add ITypeFactory and TypeFactoryProxy
isolate org.hibernate.metadata.ClassMetadata and replace by org.jboss.tools.hibernate.spi.IClassMetadata
add ICollectionMetadata interface and CollectionMetadataProxy implementations
organize imports
isolate org.hibernate.metadata.CollectionMetadata and replace by org.jboss.tools.hibernate.spi.ICollectionMetadata
isolate org.hibernate.type.Type and replace by org.jboss.tools.hibernate.spi.IType