provide a better default font for image CAPTCHA

The image CAPTCHA provides a rather crappy default font, which is some built-in PHP bitmap font. Admin has to upload an ttf him/herself to make the image CAPTCHA acceptable. The reason to not include some ttf fonts with the image CAPTCHA package are licensing issues.

But now there is the recently launched http://fontstruct.fontshop.com where you can easily create ttf fonts.
That site contains now a lot of fonts, made by its users, which are licensed under a creative commons license.
So we could now reconsider to provide some default font(s) with the image CAPTCHA package