Fix repeating groups join

This is a further step towards a full fix for the issues reported in PR-767.

PR-767 fixed the symptoms. This PR:

1. Changes the default for Include in List Query to No - I think that this is more intuitive i.e. that you only query what is displayed in the list unless you explicitly ask for other fields to be shown. However this does need the override described in the 3rd commit.

2. It tidies up a loop in fkPublished which I spotted - exactly the same functionality - just tidier IMO (though I guess this is a matter of style and so subjective).

3. It describes what is needed in group.php for a full fix. I tried to work out what to do (which I have described - but this may not be correct) and tried to work out how to code it - however this is beyond my current knowledge of how Fabrik works - so needs Rob or Hugh to code it.

Sorry that this PR is so feeble.

Paul