t.w.twcgi : module documentation

I hold resource classes and helper classes that deal with CGI scripts.

Class	CGIDirectory	Undocumented
Class	CGIScript	CGIScript is a resource which runs child processes according to the CGI specification.
Class	FilteredScript	I am a special version of a CGI script, that uses a specific executable.
Class	CGIProcessProtocol	No class docstring; 1/11 methods documented