Fixes terminating due to corrupt preferences.

(Fixes bug #19970, partly fixes FR #20366.)

(Browse SVN revision 56270)

Yes, Windows 7. I didn't try wesnoth on other windows versions.

I got this problem (Wesnoth crashing right on start) several times, mostly after restarting the computer, one time even while I was playing Multiplayer (The game crashed and didn't start anymore) and (maybe, I'm not sure) after using the Wesnoth UMC Eclipse plugin.

I found out that the preferences file seemed to be corrupted after the crash and the restart of the computer, because after deleting it, the game ran fine.
I copied the preferences file after closing wesnoth one time, and when I inserted the backup after a crash, the game ran fine, too.
I compared the "corrupted" and the working pref file, and the only noticeable difference (besides my changes) was the different line-endings ("\n" for the working and "\r\n" for the corrupted file).

I attached two working pref files, one generated after deleting the old, and one after successfully playing wesnoth (the backup I use); and one corrupted, after the in-game crash.

I had some further problems with the Windows 7 user management and wesnoth, so maybe the problem can be located there.

I hope I could help, and thank you all for this great game!