Add short names for weekdays

aleksis/core/frontend/messages/de.json

@@ -330,5 +330,14 @@
     "A_4": "Freitag",
     "A_5": "Samstag",
     "A_6": "Sonntag"
+  },
+  "weekdays_short": {
+    "A_0": "Mo",
+    "A_1": "Di",
+    "A_2": "Mi",
+    "A_3": "Do",
+    "A_4": "Fr",
+    "A_5": "Sa",
+    "A_6": "So"
   }
 }

aleksis/core/frontend/messages/en.json

@@ -320,6 +320,15 @@
     "A_5": "Saturday",
     "A_6": "Sunday"
   },
+  "weekdays_short": {
+    "A_0": "Mo",
+    "A_1": "Tu",
+    "A_2": "We",
+    "A_3": "Th",
+    "A_4": "Fr",
+    "A_5": "Sa",
+    "A_6": "Su"
+  },
   "selection": {
     "num_items_selected": "No items selected | 1 item selected | {n} items selected"
   },