[std bug] sti Rip file handle remains open?

[bazz1tv]

I've noticed that if I try to open the last STI file I've ripped via std while std is still open, Windows 10 complains about the file being used. Then I have to close (or perhaps rip another instrument) in order to access the file from SNES Tracker.

This might be related to #138.

1. Ensure this problem is not present in the Tracker. Try getting two instances of SNES Tracker open to experiment with saving one of (song, instrument, sample) from one instance and immediately load it from another.

2. Compare SdlNfd usage in SNES Tracker with std. Remember that std doesn't autocomplete saved file extensions like SNES Tracker v0.2.3 now does. So std must not be using SdlNfd fully, I guess?