base

More fragment work:

- Introduce FragmentManager as a public API, deprecating the fragment
  APIs on Activity.  (They will be removed soon.)
- Add APIs to write a fragment reference to a bundle and later retrieve
  it.
- Add Fragment API to set another fragment as its target, for delivering
  results.
- Change when onInflate() is called and formalize its meaning in relation
  to the fragment arguments that were previously introduced.
- Change onDestroyView() to always be called, regardless of when
  onCreateView() returns.  It now also is called slightly differently,
  after the view hierarchy's state is saved.
- Fix some issues with DialogFragment's lifecycle with its associated
  Dialog and state save/restore.
- Preference can now have a Bundle associated with it to provide
  arguments to a fragment.  The data for this Bundle call be supplied
  via <extra> tags under a PreferenceScreen.
- PreferenceActivity's header XML tags are now <preference-headers>
  and <header>, and you can supply <extra> tags under a <header> to set
  arguments for the header's fragment.

Change-Id: I22c212c9fa862d50840201ca16e51f9de5ef0031