A few more conversion changes:

* To go along with the previous change, XSFConfig now had internal get/set value functions that use type traits to choose between the enum and non-enum versions. (This also means I do not need to manually double-cast enums now.)
* Fix bug with the Windows API string conversions, so they do not include the trailing null byte in the output string.
* Added function to trim trailing 0s (and the decimal point if necessary) from a string that came from a double.