front: Bumped minSDK from 4 to 5.

SDK 5 needed for GLES 2.0.  minSDK=4 had been used in the manifest in
the hopes that a GLES 1.1 compatible video plugin would be implemented.
If that day ever comes, we can bump the value back down to 4.

More discussion on the topic here:
http://www.paulscode.com/forum/index.php?topic=931.0
doc: Sort changelog in descending order of user interest (my guess).

Also tweaked the last entry.  Not sure how technical we need to get on
these changelogs.  I imagine the primary purpose of the log is to alert
users to the changes that affect them the most.  Make them aware that
a game they've given up on and have stopped thinking about is suddenly
playable.  Wake them from their slumber, that sort of thing.

If I'm mistaken about the last item's impact on user experience, by all
means please revise what I wrote.