Install headers into subdirectory

... following the standard defined in
https://colcon.readthedocs.io/en/released/user/overriding-packages.html#install-headers-to-a-unique-include-directory

CMakeLists.txt

@@ -74,8 +74,6 @@ set(THIS_PACKAGE_EXPORT_DEPENDS
 # Set VERSION from package.xml
 ament_package_xml()
 
-include_directories(include)
-
 add_library(${PROJECT_NAME} SHARED
   src/aabb.cpp
   src/bodies.cpp
@@ -89,6 +87,9 @@ add_library(${PROJECT_NAME} SHARED
 )
 set_target_properties(${PROJECT_NAME} PROPERTIES VERSION ${${PROJECT_NAME}_VERSION} WINDOWS_EXPORT_ALL_SYMBOLS TRUE)
 target_compile_options(${PROJECT_NAME} PRIVATE ${PROJECT_COMPILE_OPTIONS})
+target_include_directories(${PROJECT_NAME}
+    PUBLIC $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/include>
+           $<INSTALL_INTERFACE:include/${PROJECT_NAME}>)
 target_link_libraries(${PROJECT_NAME} fcl)
 ament_target_dependencies(${PROJECT_NAME}
   ${THIS_PACKAGE_EXPORT_DEPENDS}
@@ -117,7 +118,7 @@ install(
   RUNTIME DESTINATION bin
   INCLUDES DESTINATION include
 )
-install(DIRECTORY include/ DESTINATION include)
+install(DIRECTORY include/ DESTINATION include/${PROJECT_NAME})
 
 ament_export_targets(export_${PROJECT_NAME} HAS_LIBRARY_TARGET)
 ament_export_dependencies(${THIS_PACKAGE_EXPORT_DEPENDS})