Filenames with special characters (like ;) are not properly handled by the WebApp.

To see the problem, browse this directory and try to click on the files with the following file names

;url=foo
x;url=foo

We spotted this while working on T1241 with @vlorentz; it seems that the percent-escaping of the ; and % characters should suffice, and is also needed for implementing the new PID spec from T1241