Fixed multiple bugs / WP5.0 compatible

【Contents of fixes】
■Added support for WordPress 5.0 (Gutenberg)
■Fixed the bug that meta title and meta description cannot be changed in quick edit.
■Fixed a bug that the speed of the top page slider changes faster after swiping it.
■Fixed a bug that the layout of the top page slider was broken when the search window in the header was hidden.
■Fixed a bug in the slider of the page builder.
■Fixed a bug in the “Announcements” section of the top page where tabs are not displayed when there are less than three tabs.
■Fixed a bug in the blog details page where comment.js was not being loaded.
■Fixed a bug in the footer where the SNS setting “Email Address” was not linked correctly.
■【IE】Fixed an issue where the layout would collapse when the sidebar was set to the right side.
■【IE】Fixed a bug that the blog list takes a long time to display.
■【IE】Fixed an issue where the header could not be fixed at the top.
■【IE】Corrected a bug in which the “Return to Page Top” button did not appear.
■【IE】Fixed a bug in which the layout of the top page “Achievements” was broken.

The following files have been modified for this update.
【Corrected files】
assets/js/bundle.js
assets/js/front-page.js
footer.php
functions.php
inc/load-icon.php
inc/seo.php
languages/ja.mo
languages/ja.po
pagebuilder/assets/admin/css/admin.css
pagebuilder/assets/admin/js/admin.js
pagebuilder/assets/admin/js/googlemap.js
pagebuilder/assets/css/googlemap.css
pagebuilder/assets/css/slider.css
pagebuilder/assets/js/googlemap.js
pagebuilder/modules/catchcopy.php
pagebuilder/modules/googlemap.php
pagebuilder/modules/headline.php
pagebuilder/modules/simple_table.php
pagebuilder/modules/slider.php
pagebuilder/modules/tab.php
pagebuilder/pagebuilder.php
style.css
webpack/.node-version
webpack/package-lock.json
webpack/src/front-page.js
webpack/src/index.js
webpack/src/js/header-slider.js
webpack/src/js/header.js
webpack/src/js/pagetop.js
webpack/src/js/tab-list.js

【Added files】
assets/js/comment.js
assets/js/slick.min.js