bug: Fix double encoding links in Markdown/Wiki pages
When parsing Markdown or Wiki pages, links get URL encoded. This happened
twice for links to other documents. Once explicitly and once by Wicket
when it creates a `urlFor` the page. That results in multi-byte
characters getting percent escaped, and then the percent character again
getting percent escaped.
The explicit encoding looks like a forgotten left over, so it gets
removed from the code. The Wicket encoding is smarter anyways, knowing
what is path and what is parameter.