Semantic markup: <mark>

[saschaleib]

Changes the "highlighted" menu item so it inserts a instead of the non-semantic span markup.

This also introduces a mechanism for bringing other semantic HTML tags to Wrap and hence to DokuWiki.

[saschaleib]

Following the discussion elsewhere, I have modified the hilight CSS to be applied to the <mark>tag as well, to make sure it appears correctly, even on very old browsers that have no built-in support for this tag. This also covers the wrap__dark variant that catches situations where the active template does not style this tag...