Add dict_item template filter back (we need it for #960)

apps/readux/templatetags/readux_extras.py

@@ -4,6 +4,20 @@
 register = Library()
 
 
+@register.filter
+def dict_item(dictionary, key):
+    """'Template filter to allow accessing dictionary value by variable key.
+    Example use::
+
+        {{ mydict|dict_item:keyvar }}
+    """
+    # adapted from Princeton-CDH/geniza project https://github.com/Princeton-CDH/geniza/
+    try:
+        return dictionary[key]
+    except AttributeError:
+        # fail silently if something other than a dict is passed
+        return None
+
 @register.filter
 def has_inner_hits(volume):
     """Template filter to determine if there are any inner hits across the volume"""