- Introducing the first version of the new mssql_n adodb driver (not finished, just...

- Introducing the first version of the new mssql_n adodb driver (not finished, just for experimenting).
- Now insert_record() is handling Oracle CLOBS and BLOBS properly (really annoying the number of hacks needed).
- Creating one new global object to cache $db->MetaColumns() calls per request, because it's being used
in a lot of places inside dmllib.
TODO: hack update_record() and set_field() to allow Oracle LOBs
      enclose all the Oracle function calls into one db transaction

Merged from MOODLE_17_STABLE