Add SPECCTRA dsn export and session file (.ses) import.

Original patch by Josh Jordan and Dan McMahill.  Documentation from
Bert Timmerman.

Signed-off-by: Bert Timmerman <bert.timmerman@xs4all.nl>
Updated due to hid_draw changes.

Make errors due to Ptr go away.

Signed-off-by: Bert Timmerman <bert.timmerman@xs4all.nl>