Compile lesson failed due to some header file missed.

[corndolly]

clang++ -o /tmp/.build/clang++/c++11/lesson/1.1-values -O0 -g -pthread -ftemplate-depth-1024 -ftemplate-backtrace-limit=0 -ferror-limit=1 -Wall -Werror -Wextra -std=c++11 -I . lesson/1.1-values.cpp
In file included from lesson/1.1-values.cpp:10:
In file included from ./fatal/lesson/driver.h:13:
In file included from ./fatal/lesson/lesson.h:13:
In file included from ./fatal/test/test.h:15:
In file included from ./fatal/test/string.h:13:
In file included from ./fatal/string/string_view.h:13:
In file included from ./fatal/math/hash.h:13:
In file included from ./fatal/math/numerics.h:18:
In file included from ./fatal/type/traits.h:17:
./fatal/type/data_member_getter.h:112:17: error: no member named 'addressof' in namespace 'std'
return std::addressof(ref(owner));
~~~~~^
fatal error: too many errors emitted, stopping now [-ferror-limit=]
2 errors generated.

It seems that we miss #include <memory> in /fatal/type/data_member_getter.h
#126