Fix IDE warnings, specially some related to generics

[kinow]

Found with Eclipse. Did not "organise imports" as that would generate a much bigger diff with no reason. Tests failing with several NPE, but I think it's due to some current changes in the code?

Thanks
Bruno

[aika-algorithm]

Hi Bruno,
thank you very much for those fixes! Yes, it's been a while since the last "organize imports" so I've now commited that. :-) But with the NPE's that's strange. That should not be the case. I'm using IntelliJ and i can run the tests without any of them failing. However, some are set to ignore. Even when I run the tests in maven everything seems to be in order. I have no idea. Could you have a look at it or see if you can give me a hint?

Thanks
Lukas