Drop the 'hybrid-core-sidebars' theme feature.  This allows us to get rid of extra text strings that are no longer needed.

Introduces the hybrid_register_sidebar() function, which makes it simple to register an HTML5 sidebar.
Remove the 'hybrid-core-menus' theme feature.  This just adds weight to translations.  Plus, it's already really simple to add nav menus with WordPress.
Deprecated hybrid_site_title().
Deprecate hybrid_site_description().
Soft-remove hybrid_extra_theme_headers().  This was only ever used with the old theme settings system.
Remove the plural post format functionality.  This is added weight for translations.  Plus, this is better relegated to plugins.  So, yep, I'll be porting this feature to a plugin.
Remove the `hybrid_image_content()` filter from `the_content`.  This has caused more confusion for theme authors than anything.  The function will stay for those who want to use it.
Change the `admin.css` file to `admin-widgets.css` since it now only deals with the widgets screen in the admin.
Deprecate most of the template shortcodes.  We're keeping the ones commonly-used in theme footer settings so that theme authors can continue allowing users to add these to their footer output.