[ticket/12300] Rename new class for row icon links

PHPBB3-12300
[ticket/12300] Make all topic row icons clickable

Forum list icons link to first page of forum
UCP subscribed forums icons link to first page of forum
MCP Forum page topic icons link to first (or first unread) post
PM Icons link to the message

PHPBB3-12300
[ticket/12300] Fix alignment of clickable icons

PHPBB3-12300
[ticket/12300] Fix broken link to last post in topic subscriptions list

PHPBB3-12300