Only show the possibility to allow/disallow attachments in the forum new/edit pages if the attachments package is already mounted under the forums package instance
Extend 'forum::attachments_enabled_p' with 'forum_id', so attachments ca be enabled per forum (see previous commit), and update underliying logic to make use of it.
Add column 'attachments_allowed_p' to 'forums_forums', to be used to allow/disallow attachments on a per forum basis. Currently, the attachment logic is package instance wise, so if the forums instance has an attachment instance mounted below, then attachments are assumed to be enabled for all forums in that package instance. The idea with this change is to check for both the attachments instance mounted under a particular forum instance, and the 'attachments_allowed_p' column on 'forums_forums', to decide if attachments are enabled or not (both should be true). Next step would be to rewrite the logic to achieve that.
template::reset_request_vars must be executed for all requests in the cleanupthis is already happening via "ns_ictl trace freeconn", but we keepfor the time being this as a reminder, when merging with different versions, etc.
