First maybe-usable version!
Pre-release
This version automatically saves the tournament every time something is changed, can load tournaments from save files, can load old versions/states of the tournament (so basically undo), can edit players, and can edit match results.
It still doesn't allow for manually changing the pairings, and I've done some things that might not scale well and have not tested them with really big tournaments, so it's not ready to run anything major. But I think it should be adequate for running some smallish test tournaments now.
Excalibur now requires a save file to be specified on the command line. If the file exists, the newest save in it is loaded; if it doesn't exist, it is created. If it exists but is not an excalibur save file, probably bad things happen. I didn't try it.