#1110 Selecting non-duplicates during import doesn't work.

[Michał Borek]

When importing new rules, the non-duplicate rules are not selected by default.

This is done because of RuleSetSelectionDialog.checkNonDupes() method.
Instead of getting rules from the file twice, it should be done once, and checkNonDupes method should iterate through elements in table (not fetching from file again).

You can use my patch (attachment) to quickly fix it.

[Andreas Dangel]

See also https://github.com/pmd/pmd/pull/21