unused includes (#1133)

* unused includes

Signed-off-by: Rosen Penev <rosenp@gmail.com>

* Use consistent order of includes

Always include in the following order:
- Own header files
- Standard header files
- System header files
- Project header files (toolkit first)

Exceptions:
- cppunit/extensions/HelperMacros.h must be included after
  header files declaring stream operators
- config.h must be included before its definitions are used

---------

Signed-off-by: Rosen Penev <rosenp@gmail.com>
Co-authored-by: Urs Fleisch <ufleisch@users.sourceforge.net>

examples/tagwriter.cpp

@@ -25,17 +25,16 @@
 #include <iostream>
 #include <iomanip>
 #include <cstring>
-
 #include <cstdio>
+#include <cstdlib>
 #include <sys/types.h>
 #include <sys/stat.h>
-#include <cstdlib>
 
 #include "tlist.h"
-#include "fileref.h"
 #include "tfile.h"
-#include "tag.h"
 #include "tpropertymap.h"
+#include "fileref.h"
+#include "tag.h"
 
 using namespace std;