Fixes to chapter Algorithmik der Filmsuche #4.

    * typo fixes.
    * formula explaination added.
Fixes to chapter Analyse von Libhugin #2.

    * movie rating explaination changed.
    * typo fixed.
Fixes to chapter  Zusammenfassung.

    * refs fixed and added.
    * explanation of movie rating changed.
String compare benchmark caption  updated.