Add post count, image count, and unique posters to post detail

Just like 4chan has!!!!!!!

Signed-off-by: Alek Ratzloff <alekratz@gmail.com>

board/models.py

@@ -135,6 +135,18 @@ class Post(models.Model):
             self.__make_thumbnail()
         super(Post, self).save(*args, **kwargs)
 
+    def image_replies_count(self) -> int:
+        """
+        Gets the number of image replies to this OP.
+        """
+        # I would normally use the filter() and count() functions here, but
+        # image__isnull=True does not seem to behave correctly. This is close
+        # enough.
+        return len([p for p in self.replies.all() if p.image])
+
+    def unique_posters(self) -> int:
+        return len(set(p.ip for p in self.replies.all()))
+
     def __make_thumbnail(self):
         image = Image.open(self.image)
         image.thumbnail(settings.THUMB_SIZE, Image.ANTIALIAS)