104 domain update

Solving issue #104 (closed) . As specified there, we have done the following:

• Int data objects are updated, but only the min and max value. And then, the full set of options is all the range from min to max. This is used in case we don't know the domain for the performance attributes. But still, the design parameters space can be not fully explored. Besides, the type when updating is set back to Int.
• Categorical and ordinal are not updated. These should be known by the designer

There is a test implemented also to check all this in a really simple example with Int and Categorical