Automatically create Confluence-compatible anchors for titles

Like XWiki, Confluence automatically produces anchors for titles. But the anchors are not the same, so links to these anchors are broken if we don't produce compatible anchors.

The produced anchors are not the same in Confluence Cloud and Confluence Server:

• in Confluence server, spaces are removed and the page title without space is prepended
• in Confluence cloud, spaces are converted to dashes and the page title is NOT prepended