Added top level exported function, options interface and Graphviz object interface
Added top level exported function, options interface and Graphviz object interface

markogresak/DefinitelyTyped,magny/DefinitelyTyped,mcliment/DefinitelyTyped,georgemarshall/DefinitelyTyped,borisyankov/DefinitelyTyped,georgemarshall/DefinitelyTyped,dsebastien/DefinitelyTyped,magny/DefinitelyTyped,georgemarshall/DefinitelyTyped,georgemarshall/DefinitelyTyped,dsebastien/DefinitelyTyped,borisyankov/DefinitelyTyped