Remove CVFold parameter from decision tree classifier in OpenCV 3

Summary

Remove the CVFold parameter from decision tree classifier in OpenCV 3 as it crashes. The parameter is now only avalaible when using OpenCV 2. See issue #1952 (closed).

Copyright

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changed milestone to %7.0.0

added bug + 1 deleted label

merged

mentioned in commit 618f2d30

mentioned in issue #1952 (closed)