ENH: support external tinyXML

CMake/FindTinyXML.cmake

CMake/ImportTinyXML.cmake

CMake/otbIncludeDirectories.cmake

CMakeLists.txt

Code/Fuzzy/CMakeLists.txt

Code/IO/CMakeLists.txt

Code/ObjectDetection/CMakeLists.txt

Testing/Utilities/CMakeLists.txt

Utilities/CMakeLists.txt

Utilities/tinyXMLlib/CMakeLists.txt