Improved named_scope to be used like as with_scope

Attached the patch.

+1

Removed mail headers from the patch.

I just needed this functionality not too long ago, and the implementation looks nice and simple. However, it looks like tests are missing, could you add some?

I've been playing around with this a little bit and found out you can completely remove the "with" method on the Scope class and it will still behave properly. This is because when you call "with" it will be delegated to the proxy scope and already apply with_scope.

I propose not using the "with" method at all and just sticking to with_scope. This required a couple minor changes but I've attached a patch which does this.

User.active.with_scope do
  User.count #=> equals to User.active.count
end

Ryan, I agree with you.