Merge Choosing and new Code

[sssssssssnake]

The new code regarding reading and managing files was updated.

Updated Code

public static class MusicEntry {
        public String id;
        public String filename;
        public String filepath;
}

public class MusicSheetView extends View {}
public class MathStuff {}

these are the more influential classes and will get updated through the next few days for better design patterns and easier readablility