Limiting the redirect pages

[SparoHawk]

The purpose of those redirects are the following:

1.- Give the user the option of retuning to the thread he was in, or skipping that and going back to the forum where the thread is in. You don't always want to go back to the same thread after voting or posting.
2.- In the future, it will help alleviate database server loads when there are a lot more users coming and going from the forums.