Started implementation of product.
Continuing the development of domain's product
To be reviewed
Some simple examples.
Corretti errori nei parallelotopi.
Aggiunte altre funzioni nel prodotto.
Added some methods to domain product
Merge branch 'domainProduct'
Renamed empty --> bottom
        full  --> top
Conflicts:
	core/src/main/scala/it/unich/sci/jandom/domains/numerical/Parallelotope.scala
	core/src/main/scala/it/unich/sci/jandom/domains/numerical/Product.scala