right after the merge of 4.14 release branch
+ manual fix on one line in:
* Arrangement_on_surface_2/include/CGAL/IO/Arr_text_formatter.h
* .travis/generate_travis.sh
is_streamable is a meta-function that checks if a type is streamable
is_streamable<T>::value is true iff the type T has stream operators <<
and >>. Otherwise it is false.
That commit adds a new header, used nowhere, and a new test. That cannot
break anything. I do it directly to 'next', with my own approval.