Fix sorting of threaded messages.
Fix action bar items missing when opening new message.

Calling configureMenu() inside updateMenu() doesn't update the
buttons properly. Instead, call invalidateOptionsMenu(). This forces
the menu to be re-created, and onPreareOptionsMenu() to be called.
From there, configureMenu() is called automatically.
Put back prev/next buttons to non-split message views for now.

Some people prefer them over swiping / volume keys.

They could probably be made optional so they can be hidden.

Also: delete the now unused message_view_fragment.xml and message_view_option.xml.
MessageView: Theme fix when global and message view theme differ

- Since the split-view change, MessageView is only a fragment, so we
  can't call setTheme() anymore so easily.
  Instead, use a ContextThemeWrapper and use that to inflate the
  layout. This way the message header and attachment view
  are styled correctly.

- The HTC WebView fix in SingleMessageView was returning the wrong
  background color, when message view theme and global theme differ,
  because it always used the global theme to retrieve it.
  Fix: Specifically put the light/dark values in the themes.xml,
  and get them using getContext().getTheme().resolveAttribute().
  getContext() will use the ContextThemeWrapper from above, so
  even if the global and message view themes differ, it aleays
  returns the correct one.
  The getThemeBackgroundColor() method added to the K9ActivityMagic
  interface in 309eeb72ac3c4fb2b93766550eed24e5cab39bb8 is now not
  needed anymore, and was removed.
Merge pull request #245 from m0vie/fixes

fixes for split-view changes
changelog update
Bumped manifest to 4.323
Simplify and improve message view header layout.

The star was displayed partially off-screen before.
Simplify message list item layout.
Fix typo in changelog
Another unused import.
Swap previous and next buttons in MessageViewFragment.

Makes sure to keep behaviour consistent with previous versions.
Make next/prev buttons track their state again.
Tweak animations to use the (Slightly slower) android default animation speed.
Remove the fadeout to make things look a little less weird
Make the animations slide in from the edge. (See the aforementioned comment about jankyness)

TODO: don't remove the message view until _after_ the animation runs. Before HC, that requires rather a lot more code (writing a whole animationadapter) than it should.

TODO: get the messageview to stop jumping to hide the header area as it's displayed.
Only animate the firt view transition if it's from the message list to the message view
Because we're not reusing the message view, we don't need to force scrolling. This has the side effect of cutting down on a momentary flash of message header area on display.
Fix a potential NullPointerException when rotating the device twice

When MessageListFragment is on the back stack and the device is rotated
the instance state will be restored but no new view will be created. If
the device is rotated again onSaveInstanceState() is called and we have
to take care not to assume that the views have been created.
Simplify Handler code to restore message list state
Fix restoring instance state of fragment on back stack
Avoid saved state being discarded when message list is modified