Can you become a pilot with an Asperger syndrome diagnosis in Europe?
In order to fly commercial you will need a first class medical certificate, and getting that with aspergers is going to be tough. The first consideration is the safety or people in the air and on the ground, so the criteria is conservative. Getting a first class medical would mean lots of extra hoops, even if it is possible. If you did get a medical you would then be competing against candidates who are neuro-typical, and would have to convince the airlines that you would be able to perform your job as well as non-aspergers candidates. That's not to say it's impossible, you would want to talk to a few aviation medical examiners about it to see what they say. If you can get a medical then you've got a chance, and if you are motivated enough and willing to work for it then I believe where there's a will there's a way. 

You need to consider your own temperament when going for a pilots license of any kind, whether aspergers or neuro-typical. Flying is not just about the technical details, you need to be able to work with people, first of all your instructor! In commercial flying you also need to cooperate with other pilots and work with passengers, ground crew, and cabin staff. The extreme focus on detail and depth of knowledge on aviation you might develop with aspergers can be a huge asset in some ways, however aspergers could make it very challenging to work cooperatively in the cockpit, deal with troublesome passengers, and make quick and effective decisions. Think about some scenarios:


You are FO on a flight, the captain makes a decision you do not agree with
A passenger is angry after the flight was delayed and is shouting abuse at you
You are the captain of a flight that is low on fuel and had developed an emergency. You need to very quickly opt for continuing to the destination airport or diverting, and there are problems with either choice


Do you think you would be able to successfully deal with these types of situations in the time frame you would have to work with? Not everyone is cut out for that sort of thing, whether aspergers or neuro-typical, these are scenarios all potential commercial pilots would need to be able to deal with. 

I think first you should figure out whether you like flying airplanes or not as a love of aviation and airplanes does not automatically mean you will love being at the controls. Why not go for your private license and find out? It's the first step in getting an ATPL anyway, and you could probably get a third class medical. You can then build on that if you want a career in aviation, or keep flying privately if you don't.