FindXsd.cmake
  Contributed by Frederic Heem <frederic.heem at telsey.it>:
  http://codesynthesis.com/pipermail/xsd-users/2006-March/000269.html

  See also FindXercesC.cmake:
  http://codesynthesis.com/download/xerces-c/contrib/cmake/

  Add the following commands to the CMakeLists to automatically invoke
  the xsd compiler  when a xsd file is modified:

  SET(XSD_ARGS "cxx-tree" "--generate-ostream")

  ADD_CUSTOM_COMMAND(
     OUTPUT ${CMAKE_CURRENT_BINARY_DIR}/MyXsd.cxx
     COMMAND ${XSD_EXECUTABLE}
     ARGS ${XSD_ARGS} ${CMAKE_CURRENT_SOURCE_DIR}/MyXsd.xsd
     DEPENDS ${CMAKE_CURRENT_SOURCE_DIR}/MyXsd.xsd
  )