Use os.replace where applicable (#793)

When using 
```py
os.remove(encodeFilename(filename))
os.rename(encodeFilename(temp_filename), encodeFilename(filename))
```
the `os.remove` need not be atomic and so can be executed arbitrarily compared to the immediately following rename call. It is better to use `os.replace` instead

Authored by: paulwrubel

.gitignore

@@ -19,6 +19,8 @@ cookies.txt
 *.wav
 *.ape
 *.mkv
+*.flac
+*.avi
 *.swf
 *.part
 *.part-*