Further work on fragments:

- Implement all of the state saving and restoring machinery.  This
  caused some flux in the API.
- Add ability to have fragments that are retained across activity
  instances.
- Fix some bugs.

Change-Id: Ib6b5b0752d7f8d667cfdcd3e76d127cc9b6d901b

Conflicts:
	api/current.xml
	core/java/android/app/ActivityThread.java
More fragment stuff:

- New startActivityForResult() API.
- Fragments now should have the correct lifecycle while hanging around
  in the back stack (not being destroyed and re-created).
- Rework of state save/restore to make it simpler and better.  In theory
  now any fragment (including layout and others in the hierarchy) can
  now be retained across config changes, though this hasn't been tested.

Change-Id: I2a7fe560e14e567f5675a2f172a23fca67b3e97f

Conflicts:
	api/current.xml