Added a new boost/core/functor.hpp header.

The feader defines a new functor class template that can be used to wrap
raw functions into a function object class. This is useful, for example,
for integrating std::unique_ptr and unique_resource with custom deleters
implemented as raw functions (e.g. in C libraries).

test/Jamfile.v2

@@ -189,6 +189,8 @@ run underlying_type.cpp ;
 
 run fclose_deleter_test.cpp : : : <target-os>windows:<define>_CRT_SECURE_NO_WARNINGS <target-os>windows:<define>_CRT_SECURE_NO_DEPRECATE ;
 
+run functor_test.cpp ;
+
 run pointer_traits_pointer_test.cpp ;
 run pointer_traits_element_type_test.cpp ;
 run pointer_traits_difference_type_test.cpp ;