Construct_point_2 functors be the Rep class (the base).
This avoids conversions Rep -> Point_2 -> Rep, hence
useless copies of objects.
The result_type of the functors does not change
(we therefore return a type which is only convertible
to result_type, but hopefully this is fine, and what standard
requirements on functors are anyway).
A real fix for this would require the language addition of
"forwarding constructors".
Sylvain Pion
daee2152ec