Handling of automatic line coloring

[hagenw]

Some of the figures in the documentation are generated by using the implicit plotting functionality of some functions, e.g.

time_response_wfs(X,xs,src,conf)

Since Matlab has changed its default colors, the output will no longer look the same as before and it will also deviate between Octave and Matlab.
We should find a way to avoid this, but still show the cool automatic plotting functionality of the toolbox.

Note: for changing the color in Matlab after the plot was done, one could use the following:

hline = findobj(gcf, 'type', 'line');
set(hline,'Color','red');