fixed a bug reported on the site discussions

docs/changelog/5.x.x.txt

@@ -1,6 +1,8 @@
 5.5.3
  - Lowercase file extension in importCollateral.pl while determinating file
    type.
+ - Fixed a typo in the Forum Threads that caused an error upon deleting a
+   post.
 
 
 5.5.2

lib/WebGUI/Forum/Thread.pm

@@ -110,7 +110,7 @@ Decrements the replies counter for this thread.
 
 =cut
 
-sub deccrementReplies {
+sub decrementReplies {
         my ($self) = @_;
         WebGUI::SQL->write("update forumThread set replies=replies-1 where forumThreadId=".$self->get("forumThreadId"));
 	$self->getForum->decrementReplies;