Refactor presentation builder to avoid using the HTML and velocity macros

Currently the presentation builder generates an in-line frame that points to the first slide of the presentation. All presentation slides are grouped in a ZIP archive which is attached to the target page. The HTML macro is needed because the iframe element can't be mapped to an XDOM node. The velocity macro is needed to get the URL to the first slide inside the ZIP archive without using directly the ZipExplorer plugin.

We need to refactor the presentation builder so that:

• it generates HTML elements that can be mapped to XDOM nodes
• it attaches the slide images directly to the target page