Image Accessor Integration

How to integrate the new ImageAccessor

"'The concept of image accessors is explained at Doxygen -> Related Pages -> Images. Please make yourself familiar with this concept before going on!'"

In most cases the use of those image accessors is self-explanatory. Thus, this document does not focus on explaining easy pixel value alteration. Instead mostly pointer related accesses are regarded and several guidelines are provided to replace existing code. By that, backward compatibility can be retained by applying step-by-step procedures.