-enclosingNavigationController sets a restoration identifier on the navigation controller if appropriate.

Hard to imagine a case where we want to preserve the root view controller but
not its corresponding navigation controller, as nothing would be preserved.
Add and fix state preservation for new thread view, new PM view.

* New PM view when shown from posts view.
* Thread tag (including secondary tag) in new thread view. Two fixes here:
    1. Set the selected tag on restore taking the empty tag into account.
    2. When reloading the thread tag collection view, preserve the selected
       tags.
* Awful Browser when shown from posts view.
* Delete TODO comment that's already been done.

Fixes #289.
Bump version to 2.0.4.
Delete incremental data model used during 2.0.3 development.

The data model changed twice during development of 2.0.3. To support
lightweight migration for beta users, we made two new versions of the data
model. By now, everyone either has the newest beta or I don't care if their
object store gets nuked, so let's delete the version in between and fix the
confusing names.
Merge remote-tracking branch 'origin/master'

Conflicts:
	Source/Models/Awful.xcdatamodeld/.xccurrentversion
	Xcode/Awful.xcodeproj/project.pbxproj
Back to traditional split view on iPad.

The half-baked new-style "expanding split view controller" didn't work very
well. The traditional-style split view worked great and, in retrospect, should
not have been changed.
Reword "sort bookmarks by unread" setting and require AwfulThread.unreadPosts attribute.

Might as well just call the section "Bookmarks" if all of its settings have to
do with bookmarks.

And I don't like having numeric attributes available as both NULL and a
default. Just set a default.
Update bookmarks view when "sort by unread posts" setting changes.