Multiple feature additions and bug fixes

【Details of feature additions and fixes】
■Added multi-contributor function.
■Added the ability to set the number of articles to display in the “Designed Article List 2” widget.
■Added google custom search widget.
■Fixed the display position of header ads.
■Fixed the margin of the search results screen and when the slider is not displayed.
■Fixed widget headings and minor display issues.
■Adjusted the size of thumbnails on the detailed article and archive pages, as well as on smartphones.

The following are the files that have been modified for this update.
【Added files】
coauthors-plus
co-authors-plus/co-authors-plus.php
co-authors-plus/css
css/co-authors-plus/css/co-authors-plus.css
co-authors-plus/css/guest-authors.css
co-authors-plus/js
co-authors-plus/js/co-authors-plus.js
co-authors-plus/js/guest-authors.js ・co-authors-plus/js/guest-authors.js
co-authors-plus/languages
co-authors-plus/languages/co-authors-plus-ja.mo
co-authors-plus/languages/co-authors-plus-ja.po
co-authors-plus/languages/co-authors-plus.pot
co-authors-plus/template-tags.php
widget/google_search.php
page-profile.php

【Modified files】
js/share_button.js
languages/default.mo
languages/en.mo
functions/category_style.php
functions/head.php
widgets/category_post.php
widgets/styled_post_list2.php
languages/default.po
languages/en.po
index.php
search.php
single.php
archive.php
functions.php
responsive.css
style.css

For more details, please visit the download site for purchasers of CORE (tcd027).