Bulk creation for event series dates (#848)

* copy-from things

* Some frontend

* rrule UI

* .

* Fixes

* UI improvements

* First test

* Tests

src/pretix/base/reldate.py

@@ -82,7 +82,6 @@ class RelativeDateWrapper:
             new_date = new_date.astimezone(tz)
             newoffset = new_date.utcoffset()
             new_date += oldoffset - newoffset
-
             return new_date
 
     def to_string(self) -> str:
@@ -154,6 +153,11 @@ class RelativeDateTimeField(forms.MultiValueField):
             ('absolute', _('Fixed date:')),
             ('relative', _('Relative date:')),
         ]
+        if kwargs.get('limit_choices'):
+            limit = kwargs.pop('limit_choices')
+            choices = [(k, v) for k, v in BASE_CHOICES if k in limit]
+        else:
+            choices = BASE_CHOICES
         if not kwargs.get('required', True):
             status_choices.insert(0, ('unset', _('Not set')))
         fields = (
@@ -168,7 +172,7 @@ class RelativeDateTimeField(forms.MultiValueField):
                 required=False
             ),
             forms.ChoiceField(
-                choices=BASE_CHOICES,
+                choices=choices,
                 required=False
             ),
             forms.TimeField(
@@ -176,7 +180,7 @@ class RelativeDateTimeField(forms.MultiValueField):
             ),
         )
         if 'widget' not in kwargs:
-            kwargs['widget'] = RelativeDateTimeWidget(status_choices=status_choices, base_choices=BASE_CHOICES)
+            kwargs['widget'] = RelativeDateTimeWidget(status_choices=status_choices, base_choices=choices)
         kwargs.pop('max_length', 0)
         kwargs.pop('empty_value', 0)
         super().__init__(