ADD: new track message, Entity class and Position class

libs/eigen/bench/btl/cmake/FindGMM.cmake

@@ -0,0 +1,17 @@
+if (GMM_INCLUDE_DIR)
+  # in cache already
+  set(GMM_FOUND TRUE)
+else ()
+
+find_path(GMM_INCLUDE_DIR NAMES gmm/gmm.h
+     PATHS
+     ${INCLUDE_INSTALL_DIR}
+     ${GMM_INCLUDE_PATH}
+   )
+
+include(FindPackageHandleStandardArgs)
+FIND_PACKAGE_HANDLE_STANDARD_ARGS(GMM DEFAULT_MSG GMM_INCLUDE_DIR )
+
+mark_as_advanced(GMM_INCLUDE_DIR)
+
+endif()