Merge branch '5.5' into 6.0

diff --cc wcfsetup/install/files/js/WCF.ImageViewer.js
index 5f60114c2cab7638b185cf01c800da541d46da97,aa258f83164c8a91632fb82e1d454c590168a1a9..d68ff498a0a06a765d3eec5bca1e2cb97cb0f5a8
--- 1/wcfsetup/install/files/js/WCF.ImageViewer.js
--- 2/wcfsetup/install/files/js/WCF.ImageViewer.js
+++ b/wcfsetup/install/files/js/WCF.ImageViewer.js
@@@ -897,13 -893,13 +897,13 @@@ $.widget('ui.wcfImageViewer', 
                
                this._container = $('<div class="wcfImageViewer' + (this.options.staticViewer ? ' wcfImageViewerStatic' : '') + '" />').appendTo(document.body);
                var $imageContainer = $('<div><img /><img /></div>').appendTo(this._container);
 -              var $imageList = $('<footer><span class="wcfImageViewerButtonPrevious icon fa-angle-double-left" /><div><ul /></div><span class="wcfImageViewerButtonNext icon fa-angle-double-right" /></footer>').appendTo(this._container);
 +              var $imageList = $('<footer><span class="wcfImageViewerButtonPrevious"><fa-icon size="24" name="angles-left"></fa-icon></span><div><ul /></div><span class="wcfImageViewerButtonNext"><fa-icon size="24" name="angles-right"></fa-icon></span></footer>').appendTo(this._container);
                var $slideshowContainer = $('<ul />').appendTo($imageContainer);
 -              var $slideshowButtonPrevious = $('<li class="wcfImageViewerSlideshowButtonPrevious"><span class="icon icon48 fa-angle-left" /></li>').appendTo($slideshowContainer);
 -              var $slideshowButtonToggle = $('<li class="wcfImageViewerSlideshowButtonToggle pointer"><span class="icon icon48 fa-play" /></li>').appendTo($slideshowContainer);
 -              var $slideshowButtonNext = $('<li class="wcfImageViewerSlideshowButtonNext"><span class="icon icon48 fa-angle-right" /></li>').appendTo($slideshowContainer);
 -              var $slideshowButtonEnlarge = $('<li class="wcfImageViewerSlideshowButtonEnlarge pointer jsTooltip" title="' + WCF.Language.get('wcf.imageViewer.button.enlarge') + '"><span class="icon icon48 fa-expand" /></li>').appendTo($slideshowContainer);
 -              var $slideshowButtonFull = $('<li class="wcfImageViewerSlideshowButtonFull jsTooltip" title="' + WCF.Language.get('wcf.imageViewer.button.full') + '"><a href="#" target="_blank"><span class="icon icon48 fa-external-link" /></a></li>').appendTo($slideshowContainer);
 +              var $slideshowButtonPrevious = $('<li class="wcfImageViewerSlideshowButtonPrevious"><fa-icon size="32" name="angle-left"></fa-icon></li>').appendTo($slideshowContainer);
 +              var $slideshowButtonToggle = $('<li class="wcfImageViewerSlideshowButtonToggle pointer"><fa-icon size="32" name="play"></fa-icon></li>').appendTo($slideshowContainer);
 +              var $slideshowButtonNext = $('<li class="wcfImageViewerSlideshowButtonNext"><fa-icon size="32" name="angle-right"></fa-icon></li>').appendTo($slideshowContainer);
 +              var $slideshowButtonEnlarge = $('<li class="wcfImageViewerSlideshowButtonEnlarge pointer jsTooltip" title="' + WCF.Language.get('wcf.imageViewer.button.enlarge') + '"><fa-icon size="32" name="expand"></fa-icon></li>').appendTo($slideshowContainer);
-               var $slideshowButtonFull = $('<li class="wcfImageViewerSlideshowButtonFull pointer jsTooltip" title="' + WCF.Language.get('wcf.imageViewer.button.full') + '"><fa-icon size="32" name="arrow-up-right-from-square"></fa-icon></li>').appendTo($slideshowContainer);
++              var $slideshowButtonFull = $('<li class="wcfImageViewerSlideshowButtonFull pointer jsTooltip" title="' + WCF.Language.get('wcf.imageViewer.button.full') + '"><a href="#" target="_blank"><fa-icon size="32" name="arrow-up-right-from-square"></fa-icon></a></li>').appendTo($slideshowContainer);
                
                this._ui = {
                        buttonNext: $imageList.children('span.wcfImageViewerButtonNext'),
@@@ -944,12 -940,9 +944,11 @@@
                                this.startSlideshow();
                        }
                }, this));
-               $slideshowButtonFull.click(function(event) { window.location = $(event.currentTarget).data('link'); });
                
                // close button
 -              $('<span class="wcfImageViewerButtonClose icon icon48 fa-times pointer jsTooltip" title="' + WCF.Language.get('wcf.global.button.close') + '" />').appendTo(this._ui.header).click($.proxy(this.close, this));
 +              $(`<button type="button" class="wcfImageViewerButtonClose jsTooltip" title="${WCF.Language.get('wcf.global.button.close')}">
 +                      <fa-icon size="48" name="xmark"></fa-icon>
 +              </button>`).appendTo(this._ui.header).click($.proxy(this.close, this));
                
                if (!$.browser.mobile) {
                        // clicking on the inner container should close the dialog, but it should not be available on mobile due to