What steps will reproduce the problem? Update to the Java version 1.8.0 run MutualInformationTest.testMutualInformationFeatureSelection()

What is the expected output? Test passes

What do you see instead?

What version of the product are you using? On what operating system? ClearTK 2.0.1 java version "1.8.0_40" OS X Yosemite

Comment: In the above test, the order of 'Bag_Covered:pig' and 'Bag_Covered:wolf' is changed between two version of java. The information of both cases are the same.

Fixes the issue 417.

The problem is because of HashBasedTable used in MutualInformationStats. This causes the order of featureNames in MutualInformationFeatureSelectionExtractor.train() becomes arbitarary. To fix this, I added TreeSet(featureNames) to always have the same ordering.