REFACTORED classification trainers for MSS into own classes to be able to easily add new training-strategies.

UPDATED plenty of javadocs

UPDATED template independent extraction code. Though, I doubt that the code is really meant this way as I have some troubles understanding how segments are generated (by div or <p>-tag? or by the theta-gap parameter?) Furthermore, I don't really get how only the top-5 scoring segments are used for the content prediction