More index tweaking/optimization and small thread hiding fix.

Most feature that need to be called on each index refresh don't need
to be called on every single page build, but only after building the
threads. ThreadHiding needs to be fired on each page build to ensure
that the stub summaries fit with the number of replies, so it has to
wait for the last replies to be added. This also fixes the bug where
ThreadHiding was creating one extra stub on each IndexRefresh event.

src/Filtering/ThreadHiding.coffee

@@ -4,7 +4,7 @@ ThreadHiding =
 
     @db = new DataBoard 'hiddenThreads'
     @syncCatalog()
-    $.on d, 'IndexRefresh', @onrefresh
+    $.on d, 'IndexBuild', @onIndexBuild
     Thread.callbacks.push
       name: 'Thread Hiding'
       cb:   @node
@@ -15,13 +15,15 @@ ThreadHiding =
     return unless Conf['Thread Hiding']
     $.prepend @OP.nodes.root, ThreadHiding.makeButton @, 'hide'
 
-  onrefresh: ->
-    for threadID, thread of g.BOARD.threads when thread.isHidden
-      root = thread.OP.nodes.root.parentNode
-      if thread.stub
+  onIndexBuild: ({detail: nodes}) ->
+    for root, i in nodes by 2
+      thread = Get.threadFromRoot root
+      continue unless thread.isHidden
+      unless thread.stub
+        nodes[i + 1].hidden = true
+      else unless root.contains thread.stub
+        # When we come back to a page, the stub is already there.
         ThreadHiding.makeStub thread, root
-      else
-        root.nextElementSibling.hidden = true
     return
 
   syncCatalog: ->

src/General/Index.coffee

@@ -227,6 +227,7 @@ Index =
     $.nodes Index.nodes
     Main.callbackNodes Thread, threads
     Main.callbackNodes Post,   posts
+    $.event 'IndexRefresh'
   buildReplies: (threadRoots) ->
     posts = []
     for threadRoot in threadRoots by 2
@@ -291,5 +292,5 @@ Index =
       nodes = Index.sortedNodes
     $.rmAll Index.root
     Index.buildReplies nodes
-    $.event 'IndexRefresh'
+    $.event 'IndexBuild', nodes
     $.add Index.root, nodes