Multiple bug fixes

【Contents of fixes】
■【Firefox】Fixed a bug that the loading screen does not close in WordPress 5.6.
■Optimized OGP tags.
■【Mac】Fixed a bug that Japanese and European characters may be displayed with different thickness when using some fonts.
■Fixed an error related to the login judgment in the comment section.
■Corrected the display specification of footer logo image for Retina display.
■Social Button Type 5 (Official Button) “Facebook Like Button” specification change support
■Removed “Google+” from the social button settings.

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

【Modified file】
admin/theme-options.php
comments.php
editor-style-02.css
footer.php
functions/head.php
functions/logo.php
functions/ogp.php
functions/seo.php
languages/ja.mo
languages/ja.po
pagebuilder/assets/css/pagebuilder.css
sns-btn-btm.php
sns-btn-top.php
style.css