Apply augmentation probability centrally

[ulf1]

augm_proba: Optional[float] = 1.0
"""
augm_proba : float (Default 1.0, i.e. always)
        The probability that an augmentation is applied here
"""

# run augmentation in p% of attempts
if augm_proba > scipy.stats.uniform.rvs():  # same s np.random.random()

Modi:

• Apply a proba for each augmentation type
• Joint probabilty of applying on two different augmentation types

[ulf1]

see wordaug function