Consistently present/push view controllers.

Browser and profile view controllers should be pushed on iPhone, presented on
iPad.

I also took the opportunity to clean up some boilerplate and fix some
formatting.
Shush GRMustache.
Stop pretending that a settings did change notification ever mentions more than one setting.
Add new expand/contract icons for iPad.
Delete "Theme" label on in-page settings popover.
Theme in-page settings popover.
Replace "rewind" button with simple arrow for "open drawer".
Replace obsolete "font size" icon with switch-like icon.
Fix toolbar tint color in white theme.

Was default blue instead of Awful Blue.
Fade unread count badge out a bit when it's zero.

Since we're using it in two places, extract an unreadPosts property into
AwfulThread.
Bump unread badge away from scroll indicator.