Class::method need to be refactored

[LiuYuHui]

The current shogun Machine class store the label and the features, this implementation makes the class became stateful, it is great that refactor the Machine class and the derived class to became stateless.
The basic idea is that find all the method that accesses m_labels/m_features and use the parameters passed in instead.
here is all the class::method needs to be refactored, those methods are found by this libtooling script.

[karlnapf]

This actually doesn't look that bad...everything is in the lines of train_machine, solver, objective and therefore will be easy as the refactor only needs to pass the labels to the method as a parameter. These methods typically don't rely on the machine being stateful but simple read the labels field

[gf712]

@karlnapf this is just for classifiers, there should be more coming up soon.