Add front page layout setting

[chipbennett]

Per user request, add front page layout setting:
http://wordpress.org/support/topic/oenology-front-page-layout?replies=4

[chipbennett]

This is actually already possible, simply by choosing a custom layout for the static page assigned as page_on_front; however, it seems probably more intuitive to use a global setting, since the front-page settings should all be configurable without ever touching the post-edit screen for page_on_front and page_for_posts.

[chipbennett]

The way it is implemented currently, setting the layout for the page_on_front will still override the default static front page setting. I'm not sure I would prefer that, but it is at least consistent with the rest of the layout handling.

Closing for now.