#117 Quit fails silently when settings save fails

[Eric Gundrum]

Given a corrupt settings file (probably corrupt resource fork) --
closing the settings file displays a message reporting error -199, and
the file does not close. Choosing Quit from the application menu
does not quit and displays no feedback. The only way out seems to
be to force quit.

Encountered on OS 10.3.5. Not tested on other OS versions.