Base: QuantityFormat: avoid storing formatting defaults

User defined precision and fractional inch are stored on QuantityFormat
construction making changes persistent to object life time.
Change that so until not explicitely overriden, user defined values
are always returned.

Co-authored-by: Matthias Danner <28687794+matthiasdanner@users.noreply.github.com>

src/Base/UnitsApiPy.cpp

@@ -208,9 +208,7 @@ PyObject* UnitsApi::sToNumber(PyObject* /*self*/, PyObject* args)
     }
 
     bool ok {};
-    QuantityFormat qf;
-    qf.format = QuantityFormat::toFormat(format[0], &ok);
-    qf.precision = decimals;
+    QuantityFormat qf {QuantityFormat::toFormat(format[0], &ok), decimals};
 
     if (!ok) {
         PyErr_SetString(PyExc_ValueError, "Invalid format string");