[ticket/13038] Add link to number of posts of user in viewtopic

PHPBB3-13038
Merge pull request #2926 from Senky/ticket/13038

[ticket/13038] Link user post tally to their posts

* Senky/ticket/13038:
  [ticket/13038] Add link to number of posts of user in viewtopic
Merge branch 'develop-ascraeus' into develop

* develop-ascraeus:
  [ticket/13038] Add link to number of posts of user in viewtopic