Do not allow invalid category and document names
It happened at the instance of SMV that someone renamed a category to " " (space). This breaks quite a few things, since you can no longer go to that category page / rename it to something else. We should prohibit such renamings, and make sure that only valid names can be given to a category.
Documents also have this issue - naming them " " gives an internal server error afterwards (reported by AIV/GESO), so that should also be prohibited.
Edited by jsteinmann