Refactoring of findCodeMarker-method

Refactor the method findCodeMarker in recognition.cpp and make use of the results in the return value instead of changing the reference input-value.

Currently a list of all TrackPoints (crossList) is passed by reference and all detected codes get appended to this list. Because there has to happen further processing of the detected arucoCodes, it would be more handy to just return all detected codes, process them and then only append needed codes to the crossList list.