Tiled Gallery: Images are now given a default width and height so that resizing can be done whenever without breaking yet unloaded images.
Tiled Gallery: Added setting of extra-width and extra-height attributes, since they are expected on gallery elements, but are never set after inferring their values.
Tiled Gallery: Minor cleanup of image style attribute generation in talaveras. Extracted the style attribute out of the $output variable and moved it to a separate variable.