Resolve "folder `serialization` unused"

Closes #238 (closed)

serialization/cereal/CMakeLists.txt

-INCLUDE_DIRECTORIES(${CMAKE_CURRENT_SOURCE_DIR})
-
-SET(HDRS_SERIALIZATION ${HDRS_SERIALIZATION}
-    ${CMAKE_CURRENT_SOURCE_DIR}/serialization_eigen_core.h
-    ${CMAKE_CURRENT_SOURCE_DIR}/serialization_eigen_geometry.h
-    ${CMAKE_CURRENT_SOURCE_DIR}/serialization_eigen_sparse.h
-
-    ${CMAKE_CURRENT_SOURCE_DIR}/serialization_local_parametrization_base.h
-    ${CMAKE_CURRENT_SOURCE_DIR}/serialization_local_parametrization_homogeneous.h
-    ${CMAKE_CURRENT_SOURCE_DIR}/serialization_local_parametrization_quaternion.h
-
-    ${CMAKE_CURRENT_SOURCE_DIR}/serialization_node_base.h
-
-    ${CMAKE_CURRENT_SOURCE_DIR}/serialization_sensor_intrinsic_base.h
-    ${CMAKE_CURRENT_SOURCE_DIR}/serialization_sensor_odom2d_intrinsic.h
-
-    ${CMAKE_CURRENT_SOURCE_DIR}/serialization_processor_params_base.h
-    ${CMAKE_CURRENT_SOURCE_DIR}/serialization_processor_odom2d_params.h
-    ${CMAKE_CURRENT_SOURCE_DIR}/serialization_processor_odom3d_params.h
-
-    ${CMAKE_CURRENT_SOURCE_DIR}/serialization_time_stamp.h
-
-    ${CMAKE_CURRENT_SOURCE_DIR}/archives.h
-    ${CMAKE_CURRENT_SOURCE_DIR}/io.h
-
-    PARENT_SCOPE)