FormulaToCExpressionVisitor: improve handling of OR and FP operations
Changes:
- remove unneded newline from OR operation.
- add support for FP operations IS_ZERO, IS_NAN, IS_INF.
- simplify tests.
This PR is extracted from the outdated merge-request !234 (closed) and can be directly applied to CPAchecker without the need of updating JavaSMT to a newer version.