Add CMake install support (needed by Atomic)

CMakeLists.txt

@@ -1,9 +1,10 @@
 # Copyright 2018 Mike Dev
+# Copyright 2019 Peter Dimov
 # Distributed under the Boost Software License, Version 1.0.
 # See accompanying file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt
 
-cmake_minimum_required(VERSION 3.5)
-project(BoostTypeTraits)
+cmake_minimum_required(VERSION 3.5...3.16)
+project(BoostTypeTraits VERSION "${BOOST_SUPERPROJECT_VERSION}" LANGUAGES CXX)
 
 add_library(boost_type_traits INTERFACE)
 add_library(Boost::type_traits ALIAS boost_type_traits)
@@ -16,3 +17,10 @@ target_link_libraries(boost_type_traits
         Boost::static_assert
 )
 
+include(BoostInstall OPTIONAL RESULT_VARIABLE HAVE_BOOST_INSTALL)
+
+if(HAVE_BOOST_INSTALL)
+
+    boost_install(TARGETS boost_type_traits HEADER_DIRECTORY include/)
+
+endif()