'Manifold Learning' widget does not work with PyQt5

[ales-erjavec]

Orange version

3.3.9.dev0+3d865bc

Expected behavior

Can survive initialization

Actual behavior

Does not survive initialization

Traceback (most recent call last):
  File "/Users/aleserjavec/workspace/orange3/Orange/canvas/scheme/widgetsscheme.py", line 454, in create_widget_instance
    widget.__init__()
  File "/Users/aleserjavec/workspace/orange3/Orange/widgets/unsupervised/owmanifoldlearning.py", line 175, in __init__
    self.tsne_editor = TSNEParametersEditor(self)
  File "/Users/aleserjavec/workspace/orange3/Orange/widgets/unsupervised/owmanifoldlearning.py", line 76, in __init__
    super().__init__(parent)
  File "/Users/aleserjavec/workspace/orange3/Orange/widgets/unsupervised/owmanifoldlearning.py", line 14, in __init__
    QWidget.__init__(self, parent)
TypeError: __init__() missing 1 required positional argument: 'widget'

Steps to reproduce the behavior

Attempt to place the widget on the canvas when running in an environment where PyQt5 is available.

Additional info (worksheets, data, screenshots, ...)

PyQt5 implements proper cooperative multiple inheritance, but the ManifoldParametersEditor uses a OWComponent mixin which does not.

[ales-erjavec]

Fixed as part of be3ff05c315f5d5a0c08d69834c7846717456079