Support XLSX that are defined in random order

Some software generate [Content_Types].xml file with sheets definition in random order.
Instead of having the first sheet (id = 1) defined first, it may be defined in 3rd position.
Therefore, to read the file in the correct order, sheets order need to be fixed.

tests/Spout/Reader/XLSX/ReaderTest.php

@@ -73,6 +73,28 @@ class ReaderTest extends \PHPUnit_Framework_TestCase
         }
     }
 
+    /**
+     * @return void
+     */
+    public function testReadShouldSupportSheetsDefinitionInRandomOrder()
+    {
+        $allRows = $this->getAllRowsForFile('two_sheets_with_sheets_definition_in_reverse_order.xlsx');
+
+        $expectedRows = [
+            ['s1 - A1', 's1 - B1', 's1 - C1', 's1 - D1', 's1 - E1'],
+            ['s1 - A2', 's1 - B2', 's1 - C2', 's1 - D2', 's1 - E2'],
+            ['s1 - A3', 's1 - B3', 's1 - C3', 's1 - D3', 's1 - E3'],
+            ['s1 - A4', 's1 - B4', 's1 - C4', 's1 - D4', 's1 - E4'],
+            ['s1 - A5', 's1 - B5', 's1 - C5', 's1 - D5', 's1 - E5'],
+            ['s2 - A1', 's2 - B1', 's2 - C1', 's2 - D1', 's2 - E1'],
+            ['s2 - A2', 's2 - B2', 's2 - C2', 's2 - D2', 's2 - E2'],
+            ['s2 - A3', 's2 - B3', 's2 - C3', 's2 - D3', 's2 - E3'],
+            ['s2 - A4', 's2 - B4', 's2 - C4', 's2 - D4', 's2 - E4'],
+            ['s2 - A5', 's2 - B5', 's2 - C5', 's2 - D5', 's2 - E5'],
+        ];
+        $this->assertEquals($expectedRows, $allRows);
+    }
+
     /**
      * @return void
      */