Drop methods Meal.addDish(Dish dish) and Meal.removeDish(Dish dish) which cause bugs for jruleengine.
Add date field for Meal.
Merge pull request #1 from lequana2/master

merged
Use history in setting up meal's requirements
Add cleanUp method to History
Enable generate more than one meals in one session
Merge pull request #9 from quannt24/master

Update engine