Enable more library-like use

[maxnoe]

To make this more usable for a wider range of people/experiments, it would be nice to

• Put as much logic as needed into small library functions, that are just used in the command line tools
• Have clear areas, where instrument specifics occur

[LukasNickel]

Does this include a complete redesign of the project? With a structure like:

aict_tools
    io
        read
        write
        (convert)
    physics/instrument stuff
        coordinates
        disp
    data stuff
        selection
        splitting
        feature generation
    machine learning
        train
        apply
    visualization
        performance plots
     scripts
        ...

That would certainly lead to a clearer and more scalable structure, but probably takes some time.