Fixed multiple bugs / WP5.1.1 compatible

【Contents of the fix】
■Added support for WordPress 5.1.1 (Gutenberg)
■Adjusted the tablet display.
■Fixed the wording of the theme options.
■Fixed the wording of the widget.
■When using the page builder, the contents of the page builder will also be searched.
■Fixed a bug where “Categories to display” was not displayed in Theme Options > Top Page > Content Builder > Latest Blog Posts List.
■Fixed a bug that the font size setting may not be reflected in Theme Options > Basic Settings > 404 Page Settings.
■Adjusted the display position of the title and subtitle of the 404 page.
■Fixed an issue where part of the global menu was obscured when the width of the window was less than 1024px.

The following files have been modified for this update.
【Corrected files】【Added files】
pagebuilder/assets/admin/js/simple_table.js
pagebuilder/assets/admin/js/slider.js
pagebuilder/assets/css/simple_table.css
pagebuilder/assets/js/googlemap.js
pagebuilder/modules/simple_table.php

【Deleted files】
pagebuilder/assets/img/slider_arrow1.png
pagebuilder/assets/img/slider_arrow2.png