Merge branch 'fix-categories-selection' into 'master'

Fix categories selection

Closes backlog#755

See merge request !125

searx/settings.yml

@@ -110,6 +110,7 @@ outgoing: # communication with search engines
 #
 enabled_plugins:
   - "Calculator"
+  - "Search on category select"
 #   - ...
 
 # Example to rewrite hostnames in external links