[ticket/289] Removed duplicated code from attachments.php
[ticket/289] Add method for generating select boxes in modules
[ticket/289] Add method for generating forum select boxes
[ticket/289] Add missing class variable to modules_helper
[ticket/289] Remove unneeded assignment
[ticket/289] Use generate_forum_select() in all modules
[ticket/289] Move store_selected_forums to modules_helper
[ticket/289] Fix incorrect method docs
Merge pull request #312 from marc1706/ticket/289

[ticket/289] Removed duplicated code from attachments.php