Remove unused bootstrap components from CSS

src/pretix/static/bootstrap/scss/_bootstrap_reduced.scss

@@ -0,0 +1,49 @@
+/*!
+ * Bootstrap v3.4.1 (https://getbootstrap.com/)
+ * Copyright 2011-2019 Twitter, Inc.
+ * Licensed under MIT (https://github.com/twbs/bootstrap/blob/master/LICENSE)
+ */
+
+// Core variables and mixins
+@import "bootstrap/variables";
+@import "bootstrap/mixins";
+
+// Reset and dependencies
+@import "bootstrap/normalize";
+@import "bootstrap/print";
+// @import "bootstrap/glyphicons";
+
+// Core CSS
+@import "bootstrap/scaffolding";
+@import "bootstrap/type";
+@import "bootstrap/code";
+@import "bootstrap/grid";
+@import "bootstrap/tables";
+@import "bootstrap/forms";
+@import "bootstrap/buttons";
+
+// Components
+@import "bootstrap/component-animations";
+@import "bootstrap/dropdowns";
+@import "bootstrap/button-groups";
+@import "bootstrap/input-groups";
+@import "bootstrap/navs";
+@import "bootstrap/pagination";
+@import "bootstrap/pager";
+@import "bootstrap/labels";
+@import "bootstrap/badges";
+@import "bootstrap/alerts";
+@import "bootstrap/progress-bars";
+@import "bootstrap/media";
+@import "bootstrap/list-group";
+@import "bootstrap/panels";
+@import "bootstrap/responsive-embed";
+@import "bootstrap/close";
+
+// Components w/ JavaScript
+@import "bootstrap/tooltip";
+@import "bootstrap/popovers";
+
+// Utility classes
+@import "bootstrap/utilities";
+@import "bootstrap/responsive-utilities";

src/pretix/static/pretixpresale/scss/main.scss

@@ -1,5 +1,5 @@
 @import "../../pretixbase/scss/_variables.scss";
-@import "../../bootstrap/scss/_bootstrap.scss";
+@import "../../bootstrap/scss/_bootstrap_reduced.scss";
 @import "../../pretixbase/scss/_theme.scss";
 @import "../../lightbox/css/lightbox.scss";
 @import "../../datetimepicker/_bootstrap-datetimepicker.scss";