First full version.
- completed Compatibility Options dialog
- fixed bug where checkboxes in compatibility options didn't update correctly when number was entered manually
- fixed bug where checking some checkboxes in gameplay options would result in invalid flags
- IWAD list and Map pack list can now show files in subdirectories
- added new supported filename extensions for IWADs/Maps/Mods
- dialog for selecting engine to add now shows only .exe files on Windows