* issue and changeset links generated only if the object exists
* issue subject and status appear in the link title
* strike issue link if issue is closed
* red wiki page link if page doesn't exist
* new icon for external links

Wiki page cache had to be disabled.

git-svn-id: http://redmine.rubyforge.org/svn/trunk@714 e93f8b46-1217-0410-a6f0-8f06a7374b81