Twenty Fourteen: Allow custom page templates to be set as the front page

[iamtakashi]

The theme has two custom page templates, Full Width Page and Contributor Page templates. Users should be able to use either of temaplate for the front page if they wish to.

However front-page.php was added to the theme in [25021] and this is always used for the front page as per ​the template hierarchy therefore users are not able to set any custom page template as the front page.

We probably need to remove front-page.php and move the template part for the featured content and the wrapper (We maybe remove this) to templates that can be set as the front page.

Step to reproduce (Full Width Page):

• Activate Twenty Fourteen.
• Add some widgets to content sidebar to activate the sidebar.
• Publish a page with the full width page template.
• Select the published page as front page in the reading settings.
• View the front page of the site. Content sidebar appears on the page.

Step to reproduce (Contributor Page):

• Activate Twenty Fourteen.
• Publish at least one post.
• Publish a page with the contributor template.
• Select the published page as front page in the reading settings.
• View the front pageof the site. There is no contributor is displayed.

[celloexpressions]

We should probably just do the featured content stuff if is_front_page in all of the page templates so that it automatically works regardless of them changing template. That way it should "just work" without users needing to specify a specific template for the homepage, letting them use whichever they prefer.

[iamtakashi]

Attached a patch to fix this issue.

[lancewillett]

I think this one needs more discussion. Let's bring it up during Tue office hours.

[lancewillett]

Discussed today in ​Twenty Fourteen office hours.

We agreed the approach in the patch -- though it adds more code to many template files -- is a good trade-off for allowing authors to use any page template as the front on their blog.

[lancewillett]

In 25985:

Twenty Fourteen: allow any page to be set as the front page, removing requirement for front-page.php template file. Props iamtakashi, fixes #25685.