Working on issues https://github.com/Mischback/django-oweb/issues/4 and https://github.com/Mischback/django-oweb/issues/11
Make the get_planet_queue as independent as possible

Most of the parameters should be optional. If these parameters are provided, some database queries should be obsolete.
I try to keep issue https://github.com/Mischback/django-oweb/issues/5 in mind, but this issue will be regarded on its own.
Ohhh weeee, Robo/Nani included into queue calculation

This solves issue https://github.com/Mischback/django-oweb/issues/4
Needs some testing, though...