Sync with latest Instiki trunk. Changes:

1) Upgrade Rails to 1.2.3
2) Revert RedCloth to previous version (who %#$@ cares?)
3) Preserve the Rails Security fix  to vendor/rails/actionpack/lib/action_controller/caching.rb from Revision 80.

vendor/rails/actionpack/lib/action_controller/test_process.rb

@@ -288,11 +288,11 @@ module ActionController #:nodoc:
     end
 
     def [](key)
-      data[key.to_s]
+      data[key]
     end
 
     def []=(key, value)
-      data[key.to_s] = value
+      data[key] = value
     end
 
     def update