Implement the D6.17 hook_link_alter() for comments

#374463-47: Alter comment links.

The feature is still broken in D6.16, but my patch (#1 above) was committed and will probably show up in D6.17.

This should allow us to remove forum_access_preprocess_comment() in favor of forum_access_link_alter() (aka hook_link_alter()), which will hopefully cause less conflicts with other modules and which should be easier to implement.

Starting with 6.17, Drupal passes the $comment along to hook_link_alter(), and this allows us to do without the very hackish hook_preprocess_comment().

The advantage of this patch over the one in #525392-37: Advanced Forum 1.x and Forum Access Incompatibility is that it deals only with making the links on the comments available. This means that all the other functionality, which is well-tested and stable, remains unchanged.

Please test this patch (against 6.x-1.5 or the current -dev) both with and without Advanced Forum and let us know what you find.

I'll have to cache the user_load() call. D6 doesn't.

I've committed this to the -dev version (give it up to 12h to be repackaged).

Please test this and let us know how it works, both for pre-D6.17 as well as for D6.17+, and also with or without Advanced Forum.

Note: This change only deals with whether the comment links are visible or not. It is completely safe, because it does not have any influence on the accessibility of the create, edit, and delete pages.

Hear, hear...