extend changes.xliff

changes.xlf is generated at the end of each workflow step. The needed quality markup will be added to it:

• on task-level (on level of the complete xliff-file) the task wide QA markup in a syntax as close to xliff.doc as possible
• on file-level the document wide QA markup in a syntax as close to xliff.doc as possible
• inside each segment the MQM markup in the syntax defined by DFKI
• the number of words can already be passed to translate5.
• it will be added to the changes.xlf, which is generated add the end of each workflow step as a task property.