Add a bunch of events to ACP template files which can be useful for extension authors for customizing ACP. The plan is to add ~20 events to:
acp_ban.html
acp_email.html
acp_forums.html
acp_groups.html
acp_groups_position.html
acp_logs.html
acp_permissions.html
acp_prune_forums.html
acp_prune_users.html
acp_users.html
permission_forum_copy.html