Editor: avoid duplicated line endings inbetween multiple cursors

Change-Id: Ia1721837efef47d570faa4e393b6b0b372944735
Reviewed-by: Eike Ziller <eike.ziller@qt.io>

src/libs/utils/multitextcursor.cpp

@@ -132,8 +132,11 @@ QString MultiTextCursor::selectedText() const
         const QString &cursorText = cursor.selectedText();
         if (cursorText.isEmpty())
             continue;
-        if (!text.isEmpty())
+        if (!text.isEmpty()) {
+            if (text.endsWith(QChar::ParagraphSeparator))
+                text.chop(1);
             text.append('\n');
+        }
         text.append(cursorText);
     }
     return text;