I downloaded the BsDev's .blend and I found some default.
In this .blend I use his idea to create a new cell-shading script without them.
This script use the tree color layers (red, green and blue) to better detect objects superposition. It's include in a Python script to use the current window size without weight the GPU execution.
EDIT 10 feb 2014 : I update the file with a new code. I change the outline method to a cleaner method. More you can now choose the outline color. The new method make given color pixel when the difference between current pixel color and the neighbour pixel color is greter than a given value and do nothing else. This method remove outline transprency (it was not beautiful) and remove darkening of faces and edges.
EDIT 26 apr 2014 : I've removed the subsitute function to use % operator that is built-in and I've discovered recently.
EDIT 12 june 2014 : I've found some mistakes and some possibilities for improvment so I update. I also added a little different shader that applie outline on texture too.