Sets the 2nd point for the line if RainbowType is RainbowType is set to RainbowEffect.LINE_OF_ORIGIN.
Note line of origin may be set outside of the image to stretch the rainbow further if desired.
If this value is set to nil and RainbowType is set to RainbowType is set to RainbowEffect.LINE_OF_ORIGIN, then point2 of origin will automatically be set to PointOfOrigin.X + 1, PointOfOrigin.Y + 1