fixes issue #44

The two constructors for creating shaped and shapeless recipes each have 2 params one of which is an Item and the other a Var-Arg of type Item or RecipeRow. 
Unfortunately Nashorn (the js engine bundled with Java) cannot differentiate between them even when using signature narrowing. 
Need to add createShapelessRecipe() and createShapedRecipe() static methods. I'm opening this issue pending a pull request.