Multiple bug fixes

【Contents of the fix】
■Fixed a bug in WordPress version 5 or later that the images generated by the automatic resizing process when uploading huge images are not displayed on smartphones.
■Optimized OGP tags.
■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” (app ID).
 How to get the fb:app ID required for Facebook OGP settings
■Social Button Type 5 (Official Button) “Facebook Like Button” specification change support
■Removed “Google+” from the social button 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.
■Removed unnecessary text that is output when splitting pages.

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

【Modified file】
admin/theme-options.php
comments.php
functions.php
functions/custom_page_link.php
functions/ogp.php
functions/seo.php
functions/update_notifier.php
languages/ja.mo
languages/ja.po
photek.css
sns_btn_btm.php
style.css