A lot of things...

* SearchEngine defined (missing intersection and union)
* TimedDocument defined (transcript of video+audio), contains the TimeSlots with content 
  can be merged together
* IIndex for InvertedIndex defines (for SearchEngine)
* SearchExpr for search expression (can be parsed from lisp)
* simplified IndexXMLProcessor for JAVA 7

TODO: 
SearchResult should be defined, Occurence need a mapping between a TimedDocument, which is mapped with the multimedia file with filepath attribute. Maybe a xml file...