Add method to reload dataset schema

[bruno-f-cruz]

Closes #4
Adds the method to Dataset class to reload ( dataset.reload_streams() ) all the streams in the schema.
Eg.:

stream_root_folder = r"path"
dataset = Dataset(stream_root_folder, datasetlabel='label', georeference= Georeference())

dataset.populate_streams(autoload = False)
dataset.streams.UBX.autoload=True
dataset.reload_streams(force_load=False)
dataset.export_streams()