added new landing page

app/logical/popular_post_explorer.rb

@@ -0,0 +1,30 @@
+class PopularPostExplorer
+  attr_reader :col1, :col2, :posts
+  
+  def initialize
+    load_posts
+    sort_posts
+  end
+
+private
+
+  def load_posts
+    # Post.tag_match("order:rank").where("image_width >= ?", Danbooru.config.medium_image_width).limit(5).offset(offset)
+    @posts = Post.where("image_width >= ?", Danbooru.config.medium_image_width).limit(50)
+  end
+  
+  def sort_posts
+    height1, height2 = 0, 0
+    @col1, @col2 = [], []
+    
+    posts.each do |post|
+      if height1 > height2
+        @col2 << post
+        height2 += post.medium_image_height
+      else
+        @col1 << post
+        height1 += post.medium_image_height
+      end
+    end
+  end
+end