Temporary fixed the handling of special characters in tags e.g. "µC" inside the tagcloud sidebar
"µC" tag with the "|lower"-filter does not work because the resulting html file is named "_c.html" and not "µc.html", I've just added a second array with taglinks, but it would be better to replace all "|lower" filters in the templates with an custom "|cleanurl"-filter, witch uses the same function that is used to generate the filenames e.g. utils.name_from_title.
But adding an filter inside writer.py like "env.filters['cleanurl'] = utils.name_from_title" hasn't worked: "TemplateAssertionError: no filter named 'cleanurl'".