GH 1361 Respect the filterFunctors flag during backward chaining

[ThomasThelen]

GitHub issue resolved #1361

Pull request Description:

#1361 mentions a bug where the filtered function flag wasn't being respected when backward chaining. The author fortunately outlined the places in the forward chaining path where it's respected - so adding them to the backward path was fairly straight forward. This shouldn't have any weird side effects but I haven't used the reasoner with custom filters before looking into this ticket.

In terms of testing I added a unit test that checks the filter present/absent based on the new boolean flag. If you'd like this unit test to be split into two, just let me know and I'll push another commit with the changes.

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• Tests are included.
• Documentation change and updates are provided for the Apache Jena website
• Commits have been squashed to remove intermediate development commit messages.
• Key commit messages start with the issue number (GH-xxxx)

By submitting this pull request, I acknowledge that I am making a contribution to the Apache Software Foundation under the terms and conditions of the Contributor's Agreement.

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See the Apache Jena "Contributing" guide.

[afs]

Keeping the test as-is is fine. It uses the same reasoner rather than creates a new one.