add ImageBackgroundProducer and resize util method
add image producers and renderers
add image loading and compositing utility
implement fixed text rendering functionality
make border fill in shear renderer optional
add straight line noise
update captcha with new text and image generation capabilities
allow fish eye background grid to be optional
fix formatting
Merge pull request #1 from allenplusplus/image

Add BufferedImage and Fixed Text support to Captcha image generation