The following states have to be considered:
Pysycache software: PySyCache is licensed under the GPL V2 license
Pysycache documentation: is licensed under the GPL V2 license
Pictures from additional themes: those are not GPL compliant.
In most cases, those pictures are licensed under:
a "Creative Common" license (BY, BY-NC, BY-NC-SA) which doesn't allow any commercial reuse.
an artistic license, such as the FAL
This doesn't mean that these pictures are free or that you'll obtain the copyright but you can reuse them (as long as you respect the licenses chosen by the authors).
In each pictures directory, you will find a "copyright.html" file that contain the author and the license of the pictures(Note: if I made a mistake about your copyright, please drop me an e-mail, I will correct it).