this precondition checks that global optimizers are not run on a
triangulation with weights.
Protecting balls are an exception and don't prevent global optimizers
from running
-Wunused-local-typedefs is a new warning flag of gcc-4.7, and it will enabled
by -Wall since gcc-4.8 (not yet released).
The fix is a big set of removals of unused typedefs (or comments, or moves,
depending on the context).
In global optimizers : vertices that move less than the freeze_ratio (already in documentation) stop moving for the next iterations
(merges lots of commits from Mesh_3-experimental-GF)