RainCaptcha is a CAPTCHA class that does not require any image processing extensions (GD, ImageMagick, etc). CAPTCHA was developed to be readable by humans and resistant to OCR software. It generates black-and-white images with 5 distorted letters on them and noise. Its checking algorithm is case-insensitive.
Multi-Sandbox Lua Engine (MSLE) is a modified Lua interpreter which supports creation and maintenance of multiple "100% tight" sandboxes from within Lua. "100% tight" means that the amount of memory used by a sandbox (counting both code and data) is strictly limited, a feature Lua did not offer before.