Advanced Import

Medium risk: 3 removed functions, 2 changed templates, 1 removed hook.

• The filter import_attachment_size_limit is no longer fired. Any code hooked to it stops running silently.
• The function activate_advanced_import() was removed. Direct calls from a theme or another plugin will fatal.
• The function deactivate_advanced_import() was removed. Direct calls from a theme or another plugin will fatal.
• The function prefix_demo_import_lists() was removed. Direct calls from a theme or another plugin will fatal.
• The template includes/class-theme-template-library-base.php changed. Any theme override of it is now out of date and will miss the change.
• The template includes/theme-template-library/cosmoswp.php changed. Any theme override of it is now out of date and will miss the change.