Class interface for creating components from a command-line app

A component is created with keyword arguments for stdin,stdout, stderr, environ, and argv. If the return object implements ICmdLineApp, it must use the supplied arguments. It is free to use default values for items not supplied, but it must not bypass or override any values which are supplied. E.g. it should never write to sys.stdin.

The purpose of this encapsulation is to allow application objects to be composed by other application objects, and to also allow "server" invocations of applications, as is needed for protocols like FastCGI and ReadyExec.

__call__ (
        parentComponent,
        componentName=None,
        argv=sys.argv,
        stdin=sys.stdin,
        stdout=sys.stdout,
        stderr=sys.stderr,
        environ=os.environ,
        **otherAttrs,
        )