Introduce different (configured) widgets in right sidebar

[Nagasaki45]

This change allow adding widgets to the right sidebar. The widgets can be specified in the config file using a MEDIUS_WIDGET list.

By default, the tags widget is presented, as expected. But if the user specify MEDIUS_WIDGET he will get different widgets on the sidebar.

I created 2 additional widgets: authors and categories (although they should both require extra work, I'm not so good with css...).

[Nagasaki45]

I updated the widgets. They look much better now. Take a look at my blog for a demo.

[onur]

Hey. I am glad you liked this theme and sending patches to improve. Thank you very much. You even tried to stick with the original colors.

I just tried this patch in my website and I think thumbnail in "Categories" widget needs a bit adjustments. We need a little bit more padding I guess. BTW What do you think about category list instead of a link for each category? i.e from your blog:

And I believe if we use same padding for every widget it will look much better. I can't find any free time to work on this but I really liked this widget idea and will definitely work on this.

[Nagasaki45]

I tried to make the categories widget similar to the tags widget. Maybe you are right, and it will be better to make it similar to the authors widget.
Do you like the current authors widget? Do you want me to modify the categories widget to look the same? And I didn't quite understood your comment about extra padding.

In general, I would like to follow your suggestions. Can you please elaborate?