Upgrade to Rails 2.2.0

As a side benefit, fix an (non-user-visible) bug in display_s5().
Also fixed a bug where removing orphaned pages did not expire cached summary pages.

vendor/rails/activemodel/lib/active_model/state_machine.rb

@@ -0,0 +1,66 @@
+Dir[File.dirname(__FILE__) + "/state_machine/*.rb"].sort.each do |path|
+  filename = File.basename(path)
+  require "active_model/state_machine/#{filename}"
+end
+
+module ActiveModel
+  module StateMachine
+    class InvalidTransition < Exception
+    end
+
+    def self.included(base)
+      base.extend ClassMethods
+    end
+
+    module ClassMethods
+      def inherited(klass)
+        super
+        klass.state_machines = state_machines
+      end
+
+      def state_machines
+        @state_machines ||= {}
+      end
+
+      def state_machines=(value)
+        @state_machines = value ? value.dup : nil
+      end
+
+      def state_machine(name = nil, options = {}, &block)
+        if name.is_a?(Hash)
+          options = name
+          name    = nil
+        end
+        name ||= :default
+        state_machines[name] ||= Machine.new(self, name)
+        block ? state_machines[name].update(options, &block) : state_machines[name]
+      end
+    end
+
+    def current_state(name = nil, new_state = nil, persist = false)
+      sm   = self.class.state_machine(name)
+      ivar = sm.current_state_variable
+      if name && new_state
+        if persist && respond_to?(:write_state)
+          write_state(sm, new_state)
+        end
+
+        if respond_to?(:write_state_without_persistence)
+          write_state_without_persistence(sm, new_state)
+        end
+
+        instance_variable_set(ivar, new_state)
+      else
+        instance_variable_set(ivar, nil) unless instance_variable_defined?(ivar)
+        value = instance_variable_get(ivar)
+        return value if value
+
+        if respond_to?(:read_state)
+          value = instance_variable_set(ivar, read_state(sm))
+        end
+
+        value || sm.initial_state
+      end
+    end
+  end
+end