Simple CAPTCHA: Generate and verify CAPTCHA validation images

This class can be used to generate and verify CAPTCHA validation images.

It can generate an image with a random text drawn on it that the user must read and enter the text to confirm that is a human user and not a robot.

The length of the text, the colors of the image, the background image, the text font and the text inclination angle and transparency level are configurable parameters.

The class generates the verification image as the current script output in the PNG format.