implement methods SimpleORMap::(findDistinctBySql|findDistinctEachBySql|countDistinctBySql) to allow distinct retrieval/counting of rows, fixes #1885
implement methods SimpleORMap::(findDistinctBySql|findDistinctEachBySql|countDistinctBySql) to allow distinct retrieval/counting of rows, implement SimpleORMap::buildSQLQuery() so we don't have to repeat ourselves and use new method in Course::findByUser(), fixes #1885