Securimage update to version 3.0

Convert Securimage class to PHP5
Remove support for GD fonts and multi-colored text
Add case-sensitivity option for captcha
Support for multiple captchas on one page using namespaces
Ability to show simple math problems instead of alphanumeric captchas
Remove mp3 support due to vulnerability, change to wav format
Update flash movie for sreaming wav audio
Change license from LGPL to BSD License