Nicer genre graph plotting with graphviz
provider:moodbar: increased roundoff
Moodbar sampling improved, pretty genre plot.

    Example:

        https://dl.dropboxusercontent.com/u/12859833/genre_graph.png
        https://dl.dropboxusercontent.com/u/12859833/genre_graph_middle.png
        https://dl.dropboxusercontent.com/u/12859833/genre_graph_small.png
Fix for passing plotting options through to plot.py
Merge with upstream