Add relevant_orderlist exporter

This Exporter has the most useful information in the first rows of the
exported document. Specifically the product and the custom questions.
Other fields are also resorted somewhat to place very useless columns at
the end of the table. See code for details :)

src/pretix/base/exporters/__init__.py

@@ -28,5 +28,6 @@ from .items import *  # noqa
 from .json import *  # noqa
 from .mail import *  # noqa
 from .orderlist import *  # noqa
+from .relevant_orderlist import *  # noqa
 from .reusablemedia import *  # noqa
 from .waitinglist import *  # noqa

src/pretix/locale/de/LC_MESSAGES/django.po

@@ -817,6 +817,11 @@ msgctxt "export_category"
 msgid "Order data"
 msgstr "Bestelldaten"
 
+#: pretix/base/exporters/relevant_orderlist.py:87
+msgctxt "export_category"
+msgid "Relevant Order data"
+msgstr "Relevante Bestelldaten"
+
 #: pretix/base/exporters/answers.py:56
 msgid ""
 "Download a ZIP file including all files that have been uploaded by your "
@@ -1821,6 +1826,10 @@ msgstr "Ohne gültige Mitgliedschaft verstecken"
 msgid "Order data"
 msgstr "Bestelldaten"
 
+#: pretix/base/exporters/relevant_orderlist.py:86
+msgid "Relevant Order data"
+msgstr "Relevante Bestelldaten"
+
 #: pretix/base/exporters/json.py:53
 msgid ""
 "Download a structured JSON representation of all orders. This might be "
@@ -1857,6 +1866,18 @@ msgstr ""
 "Bestellposition und das dritte eine Zeile für jede zusätzlich erhobene "
 "Gebühr."
 
+#: pretix/base/exporters/relevant_orderlist.py:88
+msgid ""
+"Download a spreadsheet of all orders. The spreadsheet will include three "
+"sheets, one with a line for every order, one with a line for every order "
+"position, and one with a line for every additional fee charged in an "
+"order. The most relevant data is in the first columns of the table."
+msgstr ""
+"Tabelle (Excel oder CSV) mit allen Bestellungen. Das erste Tabellenblatt "
+"enthält eine Zeile für jede Bestellung, das zweite eine Zeile für jede "
+"Bestellposition und das dritte eine Zeile für jede zusätzlich erhobene "
+"Gebühr. Die relevantesten Daten sind in den ersten Spalten der Tabelle."
+
 #: pretix/base/exporters/orderlist.py:100 pretix/base/models/orders.py:332
 #: pretix/control/navigation.py:255 pretix/control/navigation.py:362
 #: pretix/control/templates/pretixcontrol/orders/index.html:8