mailbox_helper.php

Merge of "in-portal/branches/5.2.x@16513" to "in-portal/branches/5.3.x@16503".

Conflicts:

• core/install.php
• core/install/install_toolkit.php
• core/kernel/application.php
• core/kernel/db/cat_event_handler.php
• core/kernel/db/cat_tag_processor.php
• core/kernel/db/db_event_handler.php
• core/kernel/db/db_tag_processor.php
• core/kernel/db/dblist.php
• core/kernel/kbase.php
• core/kernel/managers/plain_url_processor.php
• core/kernel/managers/rewrite_url_processor.php
• core/kernel/processors/main_processor.php
• core/kernel/session/session.php
• core/kernel/utility/event.php
• core/kernel/utility/formatters/multilang_formatter.php
• core/kernel/utility/temp_handler.php
• core/units/categories/categories_event_handler.php
• core/units/categories/categories_tag_processor.php
• core/units/custom_fields/custom_fields_event_handler.php
• core/units/email_templates/email_template_eh.php
• core/units/email_templates/email_template_tp.php
• core/units/favorites/favorites_eh.php
• core/units/forms/form_submissions/form_submissions_eh.php
• core/units/forms/submission_log/submission_log_eh.php
• core/units/helpers/cat_dbitem_export_helper.php
• core/units/helpers/csv_helper.php
• core/units/helpers/mod_rewrite_helper.php
• core/units/helpers/sections_helper.php
• core/units/helpers/themes_helper.php
• core/units/logs/session_logs/session_log_eh.php
• core/units/mailing_lists/mailing_list_eh.php
• core/units/modules/modules_event_handler.php
• core/units/modules/modules_tag_processor.php
• core/units/page_revisions/page_revision_eh.php
• core/units/priorites/priority_eh.php
• core/units/scheduled_tasks/scheduled_task_eh.php
• core/units/site_domains/site_domain_eh.php
• core/units/statistics/statistics_tag_processor.php
• core/units/user_groups/user_groups_eh.php
• core/units/users/users_event_handler.php

Fixes INP-1436 - PHP 7 compatibility issues

Differential Revision: http://qa.in-portal.org/D79