#5 xml files saved without xml extension

[Gus Heck]

Steps to Reproduce
1. Download and run a new copy of NATO
2. Select File > Save As... (as suggested in the help tips)
3. In the file save dialog type "Test" and click save
4. Select File > Open

Observed Behavior:
3 example files are listed with a .xml extension, and an extensionless file named "Test" is also shown.

Expected Behavior:
File save behavior in modern programs generally applies the file extension when it is omitted by the user. Also, the open dialog normally filters out inappropriate extensions. I also recommend that you check to see if the user has added an extension and respect that, and provide a filter option to view any file as well as the default filter to show only *.xml.