Postgres SchemaDumper does not preserve composite index column order

The schema dumper used by the PostgreSQL adapter does not preserve column order for composite keys. It issues a query against internal Postgres tables and does no further sorting. While this leaves it up to the DB to decide, I've found that Postgres 8.3 on MacOS X seems to return in attribute number ascending order. So, the problem wouldn't appear if every subsequent column in the index appeared later than all previous ones in the table definition. If the columns used in the index are not in the same sequential ordering as the table definition, the dumped "add_index" line is wrong.

While looking into this code, too, I noticed an artificial upper limit on the number of columns in composite indices. As of 8.3, Postgres allows up to 32 columns. The PostgreSQL adapter, however, caps this at 10.