ADD: new track message, Entity class and Position class

libs/eigen/cmake/FindGoogleHash.cmake

@@ -0,0 +1,23 @@
+
+if (GOOGLEHASH_INCLUDES AND GOOGLEHASH_LIBRARIES)
+  set(GOOGLEHASH_FIND_QUIETLY TRUE)
+endif ()
+
+find_path(GOOGLEHASH_INCLUDES
+  NAMES
+  google/dense_hash_map
+  PATHS
+  ${INCLUDE_INSTALL_DIR}
+)
+
+if(GOOGLEHASH_INCLUDES)
+  # let's make sure it compiles with the current compiler
+  file(WRITE ${CMAKE_BINARY_DIR}/googlehash_test.cpp
+  "#include <google/sparse_hash_map>\n#include <google/dense_hash_map>\nint main(int argc, char** argv) { google::dense_hash_map<int,float> a; google::sparse_hash_map<int,float> b; return 0;}\n")
+  try_compile(GOOGLEHASH_COMPILE ${CMAKE_BINARY_DIR} ${CMAKE_BINARY_DIR}/googlehash_test.cpp OUTPUT_VARIABLE GOOGLEHASH_COMPILE_RESULT)
+endif()
+
+include(FindPackageHandleStandardArgs)
+find_package_handle_standard_args(GoogleHash DEFAULT_MSG GOOGLEHASH_INCLUDES GOOGLEHASH_COMPILE)
+
+mark_as_advanced(GOOGLEHASH_INCLUDES)