Allow splitting 1945-48

src/NodaTimeSplitter.php

@@ -590,10 +590,18 @@ final class NodaTimeSplitter {
             return NodaSplitTime::genExactDate($year, $month, $day);
         }
         // Intl': 2020-12
-        if (\preg_match("/^[0-9]{4}\-[0-9]{2}$/", $datum)) { // German Y-m
+        if (\preg_match("/^[0-9]{4}\-[0-9]{2}$/", $datum)) { // German Y-m or 1912-15
             $year = \substr($datum, 0, 4);
             $month = \substr($datum, 5, 2);
-            return new NodaSplitTime($year, $year, $month);
+
+            // Assume the end is a month
+            if (intval($month) < 12) {
+                return new NodaSplitTime($year, $year, $month);
+            }
+            else {
+                $end = \substr($year, 0, 2) . $month;
+                return new NodaSplitTime($year, $end);
+            }
         }
 
         // German MM.JJJJ