Fixed double rendering of attachments and repository annotates
Add changelog entry
Merge pull request #1043 from opf/fix/double_syntax_highlighting_output

Fixes double rendering of attachments and repository annotates
uses named routes for topics/boards

This fixes the ugly routes displayed in the forum (e.g. https://www.openproject.org/topics/896?board_id=6) and shortens the code on top.

Unfortunately, the link_to_if_authorized helper does rely on the hash form for urls. Not all urls could be changed because of that.
Merge pull request #1044 from opf/fix/forum_urls