Support m-img attribute (indicates existence of downscaled version) in post building.

src/General/Build.coffee

@@ -76,6 +76,7 @@ Build =
         twidth:    data.tn_w
         isSpoiler: !!data.spoiler
         tag:       data.tag
+        hasDownscale: !!data.m_img
       o.file.dimensions = "#{o.file.width}x#{o.file.height}" unless /\.pdf$/.test o.file.url
     o
 

src/General/Build/File.html

@@ -14,7 +14,7 @@
       </a> 
       (${file.size}, ${file.dimensions || "PDF"})
     </div>
-    <a class="fileThumb?{file.isSpoiler}{ imgspoiler}{}" href="${fileURL}" target="_blank">
+    <a class="fileThumb?{file.isSpoiler}{ imgspoiler}{}" href="${fileURL}" target="_blank"?{file.hasDownscale}{ data-m}>
       <img 
         src="${fileThumb}" 
         alt="${file.size}"