'Shallow copy of the clip.
Returns a shwallow copy of the clip whose mask and audio will
be shallow copies of the clip\'s mask and audio if they exist.
This method is intensively used to produce new clips every time
there is an outplace transformation of the clip (clip.resize,
clip.subclip, etc.)'

def copy(self):

    newclip = copy(self)
    if hasattr(self, 'audio'):
        newclip.audio = copy(self.audio)
    if hasattr(self, 'mask'):
        newclip.mask = copy(self.mask)
    return newclip
