#54

Mixer
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  o Added support for rotation.
  o Added support for changing the anchor point around which fill_translation,
    fill_scale and rotation will be done from.

AMCP
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  o To support the new mixer features the following commands has been added:

    - MIXER ANCHOR -- will return or modify the anchor point for a layer
      (default is 0 0 for backwards compatibility). Example:
      MIXER 1-10 ANCHOR 0.5 0.5
      ...for changing the anchor to the middle of the layer
      (a MIXER 1-10 FILL 0.5 0.5 1 1 will be necessary to place the layer at the
      same place on screen as it was before).

    - MIXER ROTATION -- will return or modify the angle of which a layer is
      rotated by (clockwise degrees) around the point specified by ANCHOR.