Possibility to round values displayed in rules

[druzkaya]

Would be good to add an argument to round feature values in .rules_, else it's usual to have floats very high precision, which is not convenient when working with a rule as string.
Or maybe change the format to have in sublists feature_name/operator/value to facilitate the use of these information in tables or graphs.

[ngoix]

This is a good idea indeed , PR welcome :)