Add filtering by post id.

src/Filtering/Filter.coffee

@@ -127,6 +127,7 @@ Filter =
         return true if result.hide
     false
 
+  postID:     (post) -> post.ID
   name:       (post) -> post.info.name
   uniqueID:   (post) -> post.info.uniqueID
   tripcode:   (post) -> post.info.tripcode
@@ -155,6 +156,7 @@ Filter =
         subEntries: []
 
       for type in [
+        ['Post ID',          'postID']
         ['Name',             'name']
         ['Unique ID',        'uniqueID']
         ['Tripcode',         'tripcode']

src/General/Config.coffee

@@ -638,6 +638,11 @@ Config =
     ]
 
   filter:
+    postID: """
+      # Highlight dubs:
+      #/(\\d)\\1$/;highlight
+    """
+
     name: """
       # Filter any namefags:
       #/^(?!Anonymous$)/

src/General/html/Settings/Filter-select.html

@@ -1,5 +1,6 @@
 <select name="filter">
   <option value="guide">Guide</option>
+  <option value="postID">Post ID</option>
   <option value="name">Name</option>
   <option value="uniqueID">Unique ID</option>
   <option value="tripcode">Tripcode</option>