[Sketch] remove Python.h and Xerces

seems not to be necessary anymore

src/Mod/Sketcher/App/AppSketcher.cpp

@@ -20,11 +20,7 @@
  *                                                                         *
  ***************************************************************************/
 
-
 #include "PreCompiled.h"
-#ifndef _PreComp_
-# include <Python.h>
-#endif
 
 #include <Base/Console.h>
 #include <Base/Interpreter.h>
@@ -47,7 +43,6 @@
 #include "PropertyConstraintList.h"
 
 
-
 namespace Sketcher {
 extern PyObject* initModule();
 }