add new callbacks for new api api 9.69 (empty implementation)
attribute tradingClass moved to Contract struct (api 9.69)

This makes our xml files incompatible. Lets think how to deal
with this.
implement new callbacks (api 9.69)
Merge branch 'ib_proto_9.69' into next

* ib_proto_9.69:
  implement new callbacks (api 9.69)
  attribute tradingClass moved to Contract struct (api 9.69)
  add new callbacks for new api api 9.69 (empty implementation)