pymptk: fixes for install on mac (use correct tinyxml path, and correct installed lib path)
use load_environment_if_needed() to be nicer about multiple loadconfig() invocations
pymptk: cmake to search for numpy and provide its include path - fix for mac compilation
pymptk: cmake to search for numpy and provide its include path - fix for mac compilation

git-svn-id: svn+ssh://scm.gforge.inria.fr/svnroot/mptk/trunk@2097 0f77665a-23fb-0310-bc23-e91fd8efc3e1