That patch uses C++11 `<type_traits>`, and
`boost::callable_traits::is_invocable` that is available only since
1.66. If Boost<1.66, then the previous behavior (testing
`Sizing_field::FT`) is kept.
Fix issue https://github.com/CGAL/cgal/issues/3005
Wextra results in a dreadful wall of yellow in the test-suite and is
scary when using CGAL. Reduce some of the noise by silencing the
obvious cases with CGAL_USE or comments.
Add static checks in Mesh_edge_criteria_3.h
In case Sizing_field and Tr had not the same nested type Point_3, the
compilation error was very surprising. As it is a common error
(because Tr uses Weighted_point as nested Point_3, instead of Gt::Point_3),
I have added static checking to verify the types equality.