Add TBidiDictionary ownership flags

[Zigmund Bulinsh]

Hi!

Currently the TBidiDictionary does not support the ownership flags when creating. It would be useful in some case to have such an option. I know it's two dictionaries internally, but it is still reasonably easy to add such a feature with ownership handling as it can be quite useful in some cases.

Thank you in advance.

[Stefan Glienke]

Not completely trivial to implement because I need to check the order of notifications getting fired and make sure that objects are still alive and not already destroyed because they were removed from the dictionary controlling the ownerships. It's probably best to let the TBidiDictionary control the lifetime itself.