Merge some cleanup commits (part of ggeurts:customsql)

Author: oskarb

src/NHibernate.Test/SqlTest/Query/NativeSQLQueries.hbm.xml

@@ -241,8 +241,6 @@
 
 	<sql-query name="organizationautodetect" resultset-ref="org-description">
 		<!--  equal to "organizationpropertyreturn" but since no {} nor return-property are used hibernate will fallback to use the columns directly from the mapping -->
-		<return alias="org" class="Organization"/>
-		<return-join alias="emp" property="org.employments"/>
 		SELECT org.ORGID as orgid,
 		org.NAME as name,
 		emp.EMPLOYER as employer,

src/NHibernate/Impl/SessionFactoryImpl.cs

@@ -1180,8 +1180,8 @@ private IDictionary<string, HibernateException> CheckNamedQueries()
 					NativeSQLQuerySpecification spec;
 					if (qd.ResultSetRef != null)
 					{
-						ResultSetMappingDefinition definition = sqlResultSetMappings[qd.ResultSetRef];
-						if (definition == null)
+						ResultSetMappingDefinition definition;
+						if (!sqlResultSetMappings.TryGetValue(qd.ResultSetRef, out definition))
 						{
 							throw new MappingException("Unable to find resultset-ref definition: " + qd.ResultSetRef);
 						}