RWatermark: Apply watermark identifiers to images

This class is meant to process a given image by applying a watermark image that can serve as identifier of the origin of the image being processed.

The watermark image can have a color that is handled as transparent color, and can be applied with a variable opacity level within the range from 0% to 100%.

The watermark image can be applied in a fixed or a random position of the image to be process.

The original and the watermark images can be read in many formats, including GIF, JPEG, PNG, WBMP, XPM and XBM. The processed image can be generated in the formats GIF, JPEG and PNG.