patch for better accessibility of embedded images
According to the accessibility report (http://www.thirdageonline.eu/project-tao-2/software-development/mediawiki-accessibility-enhancements/) the thumbnail images on article pages are not being built properly.
This is mentioned in paragraph 1.1.1 as problem 2 and 3. I propose the attached patch to set a describing "View the media page" (tooltip-ca-nstab-media in MessagesXx.php) as the alternative text and to integrate all elements leading to the file description page into just one link.
The attached patch will make MediaWiki set a default text as the alternative (alt) attribute ('tooltip-ca-nstab-media' from MessagesXx.php). If there is no caption text set to describe the image, it sets the images' file name as a descriptive text. It also puts the thumb image and the zoom icon into one link.