Add ICriteria functionality missing in QueryOver

The following functionality exposed through ICriteria should also be available through QueryOver:

ICriteria CreateAlias(string associationPath, string alias, JoinType joinType, ICriterion withClause);
ICriteria CreateCriteria(string associationPath, string alias, JoinType joinType, ICriterion withClause);

ICriteria SetReadOnly(bool readOnly);