add readme and version bump

Author: mceachen

Diff for: README.md

@@ -336,6 +336,9 @@ When you enable ```order```, you'll also have the following new methods injected
 
 If your ```order``` column is an integer attribute, you'll also have these:
 
+* The class method ```#roots_and_descendants_preordered```, which returns all nodes in your tree,
+  [pre-ordered](http://en.wikipedia.org/wiki/Tree_traversal#Pre-order).
+
 * ```node1.self_and_descendants_preordered``` which will return descendants,
   [pre-ordered](http://en.wikipedia.org/wiki/Tree_traversal#Pre-order).
 
@@ -441,6 +444,11 @@ Parallelism is not tested with Rails 3.0.x nor 3.1.x due to this
 
 ## Change log
 
+### 3.10.0
+
+* Added ```#roots_and_descendants_preordered```.
+  Thanks for the suggestion, [Leonel Galan](https://github.com/leonelgalan)!
+
 ### 3.9.0
 
 * Added ```.child_ids```.

Diff for: lib/closure_tree/version.rb

@@ -1,3 +1,3 @@
 module ClosureTree
-  VERSION = "3.9.0" unless defined?(::ClosureTree::VERSION)
+  VERSION = "3.10.0" unless defined?(::ClosureTree::VERSION)
 end