fix buildMappings() method in ConfigurationProxy for 3.6, 4.0 and 4.3
properly return build allCollectionsMetaData in SessionFactoryProxy for 3.6, 4.0 and 4.3
IConfiguration.buildMapping() now returns IMapping, proper implementation for 3.6, 4.0 and 4.3
get rid of NPE while creating Dialect when opening mapping diagram