guest role; guide section ticking

plugins/slides/plugin.py

@@ -63,6 +63,7 @@ class SlidesPlugin(BasePlugin):
         non-admin role so a curator can manage the lobby TV + screensaver
         without full admin. Admins hold it by default."""
         return [
+            ('slides.view', 'View the slide decks', 'slides'),
             ('slides.manage',
              'Manage lobby display and screensaver slides', 'slides'),
         ]
@@ -76,7 +77,10 @@ class SlidesPlugin(BasePlugin):
                 'icon': 'image',
                 'route': '/settings/slides',
                 'position': 7,
-                'permission': 'slides.manage',
+                # The read permission: a manager holds it implicitly through
+                # the route's require_any_permission, and it is the one a site
+                # can grant to guests.
+                'permission': ['slides.view', 'slides.manage'],
             },
         ]