• Doc : Explicitely say that uvar callbacks are safely ignored for
  non-hashes.
  
• Doc : Document caveats and fix the usual set of typos.
  
• Fix : vmg_dispell() didn't check if the ext magic were ours when
  counting wizards that have uvar callbacks, resulting in a
  possible memory misread.
  
• Fix : getdata() now returns directly the data object, and no longer a
  copy. This caused a leak.
  
• Tst : Prefix author tests by 9*-.
  
• Tst : New optional author test : 95-portability-files.t, that uses
  Test::Portability::Files when it's present.
  
• Tst : New test : 14-self.t, that tests application of magic on the
  wizard itself.
  
• Tst : Move Hash::Util::FieldHash tests out of 11-multiple.t to
  15-huf.t.