9ff82bf2b3
Adding a new concept of "next" and "previous" to fragment.s Previously, fragments would either be placed onto or taken off of the stack, or would just replace the current fragment. The new next/prev capability gives the ability to run a transition that is specific to next/previous operations, such as navigating forward and backward in a list. New next/prev animations may be associated with a fragment replace operation to get the next/prev animations built into the system (next animates things up, prev animates them down). Change-Id: Ia9f3663bac009376420d845b396ac51b8e4d1647