"You are one of our top candidates." How many candidates are there likely to be? I have applied for a Ph.D. position at a research group in a European University and gotten an acknowledgement from a research unit member. His reply states "... you are one of our top candidates and we would like to pursue your application further. Can you provide us with some of your program codes and two references we can contact."

I have given them some of my codes and details of two of my professors for references. Its almost two weeks now and I've not received any feedback or rejection from them. He/They usually replied back within two working days during our earlier correspondences.

My question is "Am I rejected already?" and how many candidates are usually in a  'top candidates' list? 
(The Ph.D. position is to get the degree working with the research group and develop softwares for the group, etc.)
I wouldn't necessarily read anything into this. 

Often times there are a number of applications which might be reviewed. (For an open PhD position in my group, I might interview anywhere from three to six candidates, depending on the strength of the overall candidate pool.) 

Two weeks to go through evaluations of a number of different packages, including reviewing code and contacting references, is not unusual. Not only that, there's always the possibility that the person conducting the review has had other things come up in the interim (work commitments, vacations, or health issues, for instance).

I would wait a few more weeks, if possible, before politely inquiring about the status of your application. (For example, "I haven't heard back from you in several weeks. Could you please inform me of the status of my application?")