Use django-i18nfield library (#418)

src/pretix/control/forms/event.py

@@ -4,10 +4,10 @@ from django.core.exceptions import ValidationError
 from django.core.validators import RegexValidator
 from django.utils.timezone import get_current_timezone_name
 from django.utils.translation import ugettext_lazy as _
+from i18nfield.forms import I18nFormField, I18nTextarea
 from pytz import common_timezones
 
 from pretix.base.forms import I18nModelForm, SettingsForm
-from pretix.base.i18n import I18nFormField, I18nTextarea
 from pretix.base.models import Event, Organizer
 from pretix.control.forms import ExtFileField
 

src/pretix/control/forms/global_settings.py

@@ -1,9 +1,9 @@
 from collections import OrderedDict
 
 from django.utils.translation import ugettext_lazy as _
+from i18nfield.forms import I18nFormField, I18nTextInput
 
 from pretix.base.forms import SettingsForm
-from pretix.base.i18n import I18nFormField, I18nTextInput
 from pretix.base.settings import GlobalSettingsObject
 from pretix.base.signals import register_global_settings
 

src/pretix/control/forms/item.py

@@ -5,9 +5,9 @@ from django.core.exceptions import ValidationError
 from django.forms import BooleanField, ModelMultipleChoiceField
 from django.forms.formsets import DELETION_FIELD_NAME
 from django.utils.translation import ugettext as __, ugettext_lazy as _
+from i18nfield.forms import I18nFormField, I18nTextarea
 
 from pretix.base.forms import I18nFormSet, I18nModelForm
-from pretix.base.i18n import I18nFormField, I18nTextarea
 from pretix.base.models import (
     Item, ItemCategory, ItemVariation, Question, QuestionOption, Quota,
 )