[boardgames] Add ability to add new variants to form

vrobbler/apps/boardgames/widgets.py

@@ -0,0 +1,9 @@
+from django import forms
+
+
+class VariantSelectWidget(forms.SelectMultiple):
+    template_name = "boardgames/widgets/variant_select.html"
+
+    def get_context(self, name, value, attrs):
+        context = super().get_context(name, value, attrs)
+        return context