Fix #978 -- Allow to split names (#1049)

- [x] attendee names
- [x] Invoice address names
- [x] Data migration
- [x] API serializers
  - [x] orderposition
  - [x] cartposition
  - [x] invoiceaddress
  - [x] checkinlistposition
- [x] position API search
- [x] invoice API search
- [x] business/individual required toggle
- [x] Split columns in CSV exports
- [x] ticket editor
- [x] shredder
- [x] ticket/invoice sample data
- [x] order search
- [x] Handle changed naming scheme
- [x] tests
- [x] make use in:
  - [x] Boabee
  - [x] Certificate download order
  - [x] Badge download order
  - [x] Ticket download order
- [x] Document new MySQL requirement
- [x] Plugins

src/pretix/static/pretixcontrol/scss/_forms.scss

@@ -366,3 +366,52 @@ table td > .checkbox input[type="checkbox"] {
     box-shadow: 0 1px 3px 0 #aaa;
   }
 }
+
+@media(max-width: $screen-xs-max) {
+  .nameparts-form-group {
+    display: block;
+    input:not(:first-child) {
+      border-top-right-radius: 0;
+      border-top-left-radius: 0;
+    }
+    input:not(:last-child) {
+      border-bottom-right-radius: 0;
+      border-bottom-left-radius: 0;
+    }
+  }
+}
+@media(min-width: $screen-sm-min) {
+  .nameparts-form-group {
+    display: flex;
+    flex-direction: row;
+    input {
+      width: auto;
+      flex-basis: 0;
+      flex-grow: 1;
+    }
+    input:not(:first-child) {
+      border-bottom-left-radius: 0;
+      border-top-left-radius: 0;
+    }
+    input:not(:last-child) {
+      border-bottom-right-radius: 0;
+      border-top-right-radius: 0;
+    }
+    input[data-size="1"] {
+      flex-grow: 1;
+      flex-shrink: 4;
+    }
+    input[data-size="2"] {
+      flex-grow: 2;
+      flex-shrink: 3;
+    }
+    input[data-size="3"] {
+      flex-grow: 3;
+      flex-shrink: 2;
+    }
+    input[data-size="4"] {
+      flex-grow: 4;
+      flex-shrink: 1;
+    }
+  }
+}