commentaries: replace <img> tags with dtext links (#3586)

Replace <img> tags with dtext links, unless the <img> tag is already
inside an <a> tag.

Also strip Unicode spaces from DeviantArt commentaries.

app/logical/d_text.rb

@@ -83,7 +83,16 @@ class DText
         url = element["href"]
         %("#{title}":[#{url}]) if title.present? && url.present?
       when "img"
-        element.attributes["title"] || element.attributes["alt"] || ""
+        alt_text = element.attributes["title"] || element.attributes["alt"] || ""
+        src = element["src"]
+
+        if element.parent.name == "a"
+          alt_text
+        elsif alt_text.present? && src.present?
+          %("#{alt_text}":[#{src}]\n\n)
+        else
+          ""
+        end
       when "comment"
         # ignored
       else

app/logical/sources/strategies/deviant_art.rb

@@ -52,7 +52,7 @@ module Sources
               element["href"] = uri.to_s
             end
           end
-        end
+        end.gsub(/\A[[:space:]]+|[[:space:]]+\z/, "")
       end
 
     protected

test/unit/sources/deviantart_test.rb

@@ -65,7 +65,7 @@ module Sources
           * two
           * three
           
-          Heart  
+          "Heart":[https://e.deviantart.net/emoticons/h/heart.gif]
         EOS
 
         assert_equal(desc, @site.dtext_artist_commentary_desc)