Notifies members who have requested notification for new topics posted on a board of said posts.

• Only sends notifications to those who can *currently* see the topic (it doesn't matter if they could when they requested notification).
• Loads the Post language file multiple times for each language if the userLanguage setting is set.
• Board is specified by the $board global variable.
• Called from Post2 to notify users when a new topic is posted
• Same as NotifyUsersBoard in 1.0.x