task: don't show hidden images by default.

Part of #1356

Author: php-coder

src/main/resources/sql/image_dao_queries.properties

@@ -14,7 +14,8 @@ VALUES \
 series_image.find_by_series_id = \
 SELECT image_id \
   FROM series_images \
- WHERE series_id = :series_id
+ WHERE series_id = :series_id \
+   AND hidden = FALSE
 
 image_data.find_by_image_id = \
 SELECT d.content AS data \