move NT2_LOG_COPIES to container rather than expression
add reset member to table_view/table_shared_view, simplify constructors
allow swapping between of_size_ objects of different types
allow swapping between container of different types and container/scalar
allow swapping between owning container_shared_ref and container
allow constructing a container_ref from a scalar or a container_shared_ref
new nt2::container::alias function: tell if the memory of two tables overlaps
rewrite mtimes with new swap and alias functionality. Add container::as_terminal meta-function to check if the provided expression is a compatible terminal or if a new terminal must be computed instead.