parsing all possible inputs to assign values to the Event class

[iranroman]

#31 implements the generation of soundscapes, but prioritizing the randomness of:

Event = namedtuple(
  "Event",
  [
    "label",
    "source_file",
    "source_time",
    "event_time",
    "event_duration",
    "snr",
    "role",
    "pitch_shift",
    "time_stretch",
    "event_position",
  ],
)

We need to better define the types of values and functions that we will support for the different values of this class.