Last cleanup the definition of KVTML-2 XML for KDE4.

Last cleanup the definition of KVTML-2 XML for KDE4.
Word types were badly defined and multiple strings written in the entries.
 - For the next release word types will use the lesson class.
 - The container (KEduVocContainer, the current lesson) will be the base for Leitner, Lesson and Word Type.
Rename some writeType to writeWordType.
Update the dtd

svn path=/trunk/KDE/kdeedu/libkdeedu/; revision=742066