Add events to modify content status variables

Add an events in posting.php and ucp_pm_compose.php

**On lines after initialization of -> // HTML, BBCode, Smilies, Images and Flash status

And before -> // Save draft

Suggested name of events: 

- core.posting_content_statuses_settings, 

- core.pm_content_statuses_settings

To allow overwrite them in user's extension

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The reason of such minor fix is i had a task to allow administrators and moderators use links in posts and private messages with disabled Allow links in posts/private messages in ACP Post settings