Fix issues 5158104 and 4981556 (fragment problems)

5158104: com.android.contacts: java.lang.IllegalStateException:
Can not perform this action after onSaveInstanceState at
android.app.FragmentManagerImpl.checkStateLoss(FragmentManager.java:1201)

The ViewPager can just commit without worrying about a state loss,
since it can correctly reconstruct its state later.

4981556: Fragment.mImmediateActivity doesn't get restored on orientation change

I am giving up on this thing; I just don't see how it can actually
be correct.  So now instead of getting an exception about a dup
add/remove at point of the add/remove call, this will happen later when
processing the transaction.

Also add an API for controlling the visibility of menus, which ViewPager
can use to have the correct menus shows.  And add a method to get the
name of a back stack entry.

Change-Id: Idcba14cfa2a172545a7a2a2c466cb49ceb789619