Port of CgiHttpKernel to FastCGI (FCGI).
This is the same idea as the CGI kernel, but faster. And slightly more annoying, because you need to configure a port and bind to it. But as a result, it's significantly faster.
It enables testing at the FastCGI process boundary. It's compatible with any process that exposes a FastCGI interface. It's compatible with any library that consumes an HttpKernel.
There are still some bugs (see skipped tests). Pull requests highly appreciated.
Based on adoy/PHP-FastCGI-Client and igorw/CgiHttpKernel.