* Change: In Hurricane::SharedPath, the hash for the shared pathes, which
    serves for Map<> storing, were computed "on the fly" at each
    ::getHash() call, and were involving recursive calls of all the
    hashes along the components of the shared path. This is terribly
    slow especially in a design with a deep hierarchy (typical case
    LS180).
      Now, at the cost of one supplemenental unsigned long in each
    SharedPath, it is only computed once in the constructor, and is
    no longer recursive (only access the *first* tail, if any).
      As a consequence, the re-display computation delay becomes
    bearable. But also speed up any transhierarchical walkthough.