Add two augmentation functions: rotate and light change

[qizhen816]

1. bounding box and polygon/mask rotate

• Using OpenCV getRotationMatrix2D to get rotaton matrix from the angle given by config files.

• Bounding box points are calculated as well as polygon instance points.

• Binary mask rotate code is uploaded but note tested yet due to the lack of dataset.

• before:

• after(-20 degree):

2. image vertical/horizontal linear light change

• Given a linear light interval limit L, then the image light will be linearly adjusted within [-L, L].
• The function is separated to work vertically or horizontally.
• before:
  
• after(L=100, vertical):
  
• after(L=100, horizontal):
  

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