Add explicit descriptor allocation and release.

Keep track of bound columns to check if SQLGetData is valid. (may not be 
posible).

Pass any connect and env attr onto driver when connected.

Handle Env attrs (Set/Get EnvAttr).

GetDescField needs finishing.

Manage file DSN's.

Interface to Cursor and Translator libs.

Clear errors at the start of each function.

Handle SQLCopyDesc where the source and destination is on different connections.

SQLBulkoperations needs some conditions testing.

SQLBrowseConnect needs some conditions testing.
