* Move #set_cookie and #delete_cookie inline to optimize. These optimizations should
almost certainly be sent back upstream to Rack. The optimization involves using
an ivar for cookies instead of indexing into the headers each time.
* Was able to use a bare Hash for headers now that cookies have their own joining
semantics (some code assumed that the raw cookies were an Array).
* Cache blankness of body on body=
* Improve expand_cache_key for Arrays of a single element (common in our case)
* Use a simple layout condition check unless conditions are used
* Cache visible actions
* Lazily load the UrlRewriter
* Make etag an ivar that is set on prepare!
* It is not possible to always pre-determine the layout before going to ActionView.
This was *already* broken for render :partial => @object, :layout => true. This is
now handled by overriding render_to_body in layouts.rb and manually injecting the
partial's response. This needs to be done in ActionController since ActionController
knows enough to get _layout_for_option. There is probably a better abstraction here.
* As a result, all partial rendering can correctly restrict their layouts to the mime
type of the rendered partial. This could have previously caused a bug in some edge cases.
* If other layout-like options are added, they might need to add special code for the
case of render :partial. We should try to think of an alternate solution, if possible,
but this works for the cases we know of now.
