sql.py: mk_select(): Implemented DISTINCT ON according to the distinct_on param

sql.py: mk_select(): Added distinct_on param to set the columns to SELECT DISTINCT ON

sql.py: clean_name(): Convert names to lowercase so that PostgreSQL will behave the same whether the name is escaped with "" or not. This will help avoid bugs in code that uses temp tables created by the sql module.

sql.py: put_table(): Added order_by=None wherever rows were not supposed to be re-ordered. On DuplicateKeyException: Save existing pkeys in temp table for joining on.

db_xml.py: put_table(): Pass limit and start to sql.put_table()

db_xml.py: put_table(): Added limit and start options

sql.py: When creating a temporary entity (table, function, etc.), instead create it as a permanent entity in debug mode so it can be viewed after the program is run

sql.py: DbConn: Store whether in debug mode (log_debug != log_debug_none) for easy use by methods

bin/map: connect_db(): Turn on autocommit mode in debug mode if commit is on, so that incremental results can be seen in the DB

sql.py: DbConn: Use internal autocommit handling instead of DB connection autocommit attr to avoid autocommits inside a savepoint