AltoFocus: Remove custom [flexslider_gallery] shortcode

[allancole]

Nothing is actually broken here, but while submitting this theme to wporg, I got a warning about this custom shortcode that is not allowed in the theme. This custom [flexslider_gallery] shortcode is used to replace slideshow galleries (specifically) with a full-width flexslider slideshow that appears above the post title on single posts.

After looking into this, it appears the same functionality can be achieved using a filter on post_gallery. A filter is a much safer approach and less code is required to achieve the exact same result.

I should note that the custom [flexslider_gallery] shortcode is not publicly mentioned anywhere, since only the theme use it to replace the default [gallery] shortcode when the slideshow type is selected. No users would know it even exists without digging into the code. Removing it in favor of a more wporg-friendly filter will not cause any disruption for wpcom users.

[allancole]

Just pushed a commit that should fix this. ^^

To test the fix, first create a gallery with the default shortcode: [gallery ids="123,124,125"] and you should see the standard gallery output in the_content below the post title.

Then, create a slideshow gallery like: [gallery ids="123,124,125" type="slideshow"] and confirm that the gallery gets removed from the_content and placed above the post title as a full-screen flexslider slideshow gallery.

[allancole]

Fixed in: 6d101a1