Generates dynamic CSS stylesheet for a random image

Usage:

<link rel="stylesheet" type="text/css" href="/typo3conf/ext/yourextension/Resources/Public/Css/random-image.css.php?path=fileadminsubdir&css=%2ErandomImage" media="all">

Generates a stylesheet containing:

.randomImage { background-image:url("/fileadmin/fileadminsubdir/random/one-of-the-images.jpg") }