Multiple bug fixes

【Contents of the fix】
■OGP tag optimization
■Changed Facebook OGP setting from old specification (fb:admins) to new specification (fb:app_id).
※Please refer to the following article about how to get “fb:app_id” (application ID).
 How to get the fb:app ID required for Facebook OGP settings
■【Mac】Fixed a bug that the thickness of Japanese and European characters may be displayed differently when using some fonts.
■Fixed an error related to the login judgment in the comment section.
■Fixed a notice error in the comment section of the post page.
■Social Button Type 5 (Official Button) “Facebook Like Button” specification change.
■Removed “Google+” from the settings of social buttons.
■【iPhone】Fixed an issue where the Hatena bookmark icon was not displayed on the share button in the fixed footer bar.

The following are the files that have been fixed for this update.

【Modified file】
admin/theme-options.php
comments.php
editor-style-01.css
footer-bar/footer-bar.css
footer-bar/footer-bar.php
functions.php
functions/custom_page_link.php
functions/ogp.php
functions/seo.php
functions/update_notifier.php
japanese.css
languages/ja.mo
languages/ja.po
sns_btn_btm.php
sns_btn_top.php
style.css
widget/google_search.php

【Added files】
img/common/hatenabookmark-logomark.svg