Previously, constants that are defined via an expression
were evaluated using standard (integer or floating point) arithmetic,
even in parametric or exact model checking mode.
This commit provides the infrastructure for requesting that constant
expressions are evaluated using exact arithmetic.
To keep the API backward compatible, we introduce additional methods that
offer an 'exact' flag, but keep the old methods as well. Those default to
normal arithmetic.
TypeDouble constants are kept as rational numbers, while int and boolean
constants are converted to Java data types. For int, an exception is raised
if the value can't be exactly represented by Java int.