Add Boost 1.59

CMakeLists.txt

@@ -123,7 +123,9 @@ IF ( ASSIMP_ENABLE_BOOST_WORKAROUND )
   MESSAGE( STATUS "Building a non-boost version of Assimp." )
 ELSE ( ASSIMP_ENABLE_BOOST_WORKAROUND )
   SET( Boost_DETAILED_FAILURE_MSG ON )
-  SET( Boost_ADDITIONAL_VERSIONS "1.47" "1.47.0" "1.48.0" "1.48" "1.49" "1.49.0" "1.50" "1.50.0" "1.51" "1.51.0" "1.52.0" "1.53.0" "1.54.0" "1.55" "1.55.0" "1.56" "1.56.0" "1.57" "1.57.0" "1.58" "1.58.0" )
+  IF ( NOT Boost_ADDITIONAL_VERSIONS )
+    SET( Boost_ADDITIONAL_VERSIONS "1.47" "1.47.0" "1.48.0" "1.48" "1.49" "1.49.0" "1.50" "1.50.0" "1.51" "1.51.0" "1.52.0" "1.53.0" "1.54.0" "1.55" "1.55.0" "1.56" "1.56.0" "1.57" "1.57.0" "1.58" "1.58.0" "1.59" "1.59.0")
+  ENDIF ( NOT Boost_ADDITIONAL_VERSIONS )
   FIND_PACKAGE( Boost )
   IF ( NOT Boost_FOUND )
     MESSAGE( FATAL_ERROR