Source definition hooks

Hi! First, as always, thanks for the module.

I'm currently making a facebook app, where users can vote on content. My app will work with several pages doing easy facebook contests.

Anyway, the big problem is that I don't want to create every single user just for voting. I want to use the facebook user id as a source, doing that I will not populate my users table with thousands or maybe more users just for a vote.

Currently I had to modify the voting api... and yes, I know it's sad to fork a module... but apparently it was the only way.

Below I list the 2 simple changes:

In _votingapi_prep_vote: 'vote_source' => $facebook->getUser(),
In votingapi_current_user_identifier: $criteria['vote_source'] = $facebook->getUser();

These tiny modifications work great with facebook users... Hence, if you provide hooks on these functions that allow set the source, people will be able to set different sources in different situations.

By the way, in my case, using anonymous users is not a solution. In a cyber, many people can log in in the same machine, with facebook accounts and can't vote if someone already vote on that machine... Also, a person can vote multiple times opening his/her facebook session from different computers.

Beyond my project and Facebook recipes, I think that are many services which allow us to identify a user, and would be a valuable addition if we could set the source to integrate those services for good.

Thanks for reading... I hope you understand my English :)