updated CHANGES for 3.6.2 tag release.

updated CHANGES.

easily be made anyway before 3.7.0 is released.

fix a bug where exceptions thrown during __setitem__ for an ordered container leaves a bad key in the ordering.

there is a full backward compatibility

Previous BTreeContainer used to store their data in _SampleContainer__data.

    setting an existing item does not change the size,
    and the event subscribers should see the new size instead of the old size.
- Reimplemented the BTreeContainer so that it directly accesses the btree
  methods (removed the #TODO)

    - prevent the namechooser from failing on '+', '@' and '/'
    - added tests in the namechooser
    - be sure the name chooser returns unicode

Substitute zope.app.zapi by direct calls to its wrapped apis. See bug 219302. Also added a test for the CheckDependency function

  ``items``, ``keys``, and ``values`` methods with the same semantics as for
  a BTree object.  The extended interface is implemented by the
  ``BTreeContainer`` class.