Merge pull request #2 from sdestercke/master

merge versions
Adding "remove_col" method to arff object

Permitting the removal of a column/attribute of the arff data.
Updating init files

Using "*" for importing modules
Merge pull request #3 from sdestercke/master

Merge corrections about discretization
Merge pull request #3 from genyang/master

Add "remove_col" to arff.py and improve "init" files