The edge filter example contains all implemented filters apart from the Prewitt filter. Added the Prewitt filter to the example and compared it to the Scharr filter showing that Prewitt is even less rotationally invarient than the Sobel filter. Also added description.
The edge filter example contains all implemented filters apart from the Prewitt filter. Added the Prewitt filter to the example and compared it to the Scharr filter showing that Prewitt is even less rotationally invarient than the Sobel filter. Also added description.

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