Split singe file into set of src files

bin/dartsunfish.dart

@@ -1,4 +1,4 @@
-import 'package:dartsunfish/dartsunfish.dart' as dartsunfish;
+import 'package:dartsunfish/index.dart' as dartsunfish;
 
 void main(List<String> arguments) {
   dartsunfish.GameBot().playGame();