Update Images in Lecture OLAP

[melsigl]

Update and extend images in lecture 5 OLAP:

• Update images to use relative positioning to make resizing and moving single elements easier.
• Update the image on slide "Cube: A Lattice of Cuboids" to conform to Figure 4.5 on page 139 of the book (some texts are missing). Additionally, put text in the foreground, lines in the background, and maybe use a different color for the lines.
• Optionally, in image on slide "Data Warehouse Development: A Recommended Approach" use color coding for "Model refinement" lines.