added addclass filter

evennia/web/website/templatetags/addclass.py

@@ -0,0 +1,16 @@
+from django import template
+
+register = template.Library()
+
+@register.filter(name='addclass')
+def addclass(field, given_class):
+    existing_classes = field.field.widget.attrs.get('class', None)
+    if existing_classes:
+        if existing_classes.find(given_class) == -1:
+            # if the given class doesn't exist in the existing classes
+            classes = existing_classes + ' ' + given_class
+        else:
+            classes = existing_classes
+    else:
+        classes = given_class
+    return field.as_widget(attrs={"class": classes})