jQuery3 support/fixing layout bugs

【Contents of the fix】
■jQuery3 support
■Fixed a bug that caused the layout to collapse depending on the browser width.

The following files have been modified for this update.

【Modified files】
admin/js/cf-media-field.js
admin/js/my_script.js
functions/update_notifier.php
js/jscript.js
languages/ja.mo
languages/ja.po
style.css
style_sp.css
widget/google_search.php