Lack of hooks to detect when a "CustomOption" is deleted

Overview

When a "CustomOption" is deleted, no hooks fire because all database operations are done via the CRM_Core_DAO::executeQuery method.

Reproduction steps

1. Delete an Option on, for example, a Custom Field of Data Type "Alphanumeric" and Field Type "CheckBox".
2. No hooks fire.

Expected behaviour

At minimum civicrm_pre and civicrm_post should fire.

I realise that this papers over the way in which Options are handled for Custom Fields (i.e. they should probably be handled using the same logic as other OptionValues) but rebuilding the CustomOption system isn't on my radar at the moment - sorry!

Comments

PR that introduces civicrm_pre and civicrm_post hooks to follow.