Break up largo_byline to make it more modular.

[benlk]

Right now, it's a huge function: https://github.com/INN/Largo/blob/master/inc/post-tags.php#L84-L169

Make it a wrapper function around an action, maybe? The action would need to pass as arguments everything passed to largo_byline.

function largo_byline( $echo = true, $exclude_date = false, $post = null  ) {
    ...
    ob_start();
    do_action( 'largo_byline_action', array($echo, $exclude_date, $post) );
    // and on that is hooked with `add_action('largo_byline_action', name, priority, 3);` codex.wordpress.org/Function_Reference/do_action
    // - the author: https://github.com/INN/Largo/blob/master/inc/post-tags.php#L105-L142
    // - a separator
    // - the date: https://github.com/INN/Largo/blob/master/inc/post-tags.php#L146
    $output = ob_get_clean();

    $output = apply_filters( 'largo_byline', $output );

    // - the edit link and the separator before it: https://github.com/INN/Largo/blob/master/inc/post-tags.php#L159-L161
    // - echo vs return: https://github.com/INN/Largo/blob/master/inc/post-tags.php#L163-L167
}

The priorities of the actions on largo_byline_action should be separated by 10, to give us room to add new child theme actions in the middle, such as the twitter icon used in many child themes.

[benlk]

In the current version of the branch with this work, c98d8ac, inc/post-tags.php is 1003 lines long, with the following breakup, by my rough count:

• 290 lines for byline-related functions: largo_time, largo_author, largo_author_link, largo_byline, largo_byline_component_authors, largo_bline_component_publish_datetime, largo_byline_component_edit_link, largo_byline_component_sep, largo_byline_coauthors, largo_byline_normal_or_custom,
• 260 lines for post social functions: largo_post_social_links, largo_floating_social_buttons, largo_floating_social_button_width_json, largo_floating_social_button_js
• 160 lines for pagination functions: largo_entry_content, largo_custom_wp_link_pages, largo_content_nav,
• 100 lines for excerpts: largo_excerpt, largo_trim_sentences,
• 60 lines for comments: largo_comment,
• 30 lines for post type icons: post_type_icon,
• 50 lines for hero images: largo_hero_class, largo_hero_with_caption,
• 20 lines for HTML metadata: largo_post_metadata

Can we break this up somehow?

• The hero images stuff needs to move into inc/featured-media.php at least
• Social stuff could probably go in its own file, with largo_social_links from inc/helpers.php
• largo_post_metadata should go wherever largo_seo stays (currently inc/helpers.php)
• Byline stuff might have a case for breaking off into its own file for byline stuff

Mostly, this file is getting unorganized and unwieldy.

[benlk]

Also:

• add twitter handle to normal users
• add twitter handle to coauthors
• add avatar to normal users
• add avatar to coauthors
• make the author things for normal users easier to modify
• make the author things for coauthors easier to modify
• css for authors avatars
• css for author twitter handles; see RNS theme
• test that the default = '' works for authors without set avatars.
• stub tests and create ticket for creating tests