knumber_float the precision is specified via setDefaultFloatPrecision
Sync with kcalc.
Fix failing test "Precision >= 1000: (KNumber(1) + KNumber(\"1e-980\")) - KNumber(1)".
Sync with kcalc.
Fix failing test "Precision >= 1000: (KNumber(1) + KNumber(\"1e-980\")) - KNumber(1)".