Cannot style specific Panels because of limited HTML class attribute generated

In macros.vm we have:

  #set ($specialClassAttribute = $util.convertToAlphaNumeric($paneldoc.name))
...
<div class="panel expanded $!specialClassAttribute">

So if the paneldoc is for example Menu.menu1.WebHome then $paneldoc.name will be WebHome which isn't nice. All entries created with the Menu app are nested pages and thus all panels created with the Menu app will have "<div class="panel expanded WebHome">" which is not nice and doesn't allow for custom styling.

We should serialize the full reference instead.