make sure loading viewer for the first time add query param to get latest version of img, and when we leave viewer reset document.viewing

internal/js/view_support.js

@@ -186,7 +186,7 @@ function ViewImageOrVideo()
     if( ! document.viewing ) return
     if( document.viewing.type.name == 'Image' )
     {
-        im.src='../' + document.viewing.FullPathOnFS
+        im.src='../' + document.viewing.FullPathOnFS + '?t=' + new Date().getTime();
         $('#video_div').hide()
         if( $('#fname_toggle').prop('checked' ) )
             $('#img-cap').show()
@@ -623,6 +623,8 @@ function goOutOfViewer()
     // hide viewer div, then show files_div
     $('#viewer_div').addClass('d-none')
     $('#files_div').removeClass('d-none')
+    // no longer viewing an image too
+    document.viewing=null
 }
 
 // change the viewer to the previous entry (handle page change too)