Add entity highlight when accessing a Forum URL

Entities are referenced in the Permalink functionality and also on Flag.

Examples:

• Topic
  http://localhost:8080/xwiki/bin/view/Forums_Jobs/Topic
• Answer
  http://localhost:8080/xwiki/bin/view/Forums_Jobs/Topic#TopicAnswer
• Comment
  http://localhost:8080/xwiki/bin/view/Forums_Jobs/Topic#xwikicomment_TopicAnswer_0

Without looking at the URL is hard to determine what entity the Flag is referring to.