Of course, that cleanup I did earlier in which I rationalised all

the various `yes/no/maybe' enums into one common one missed a vital
point: all those enums mapped on to integers in different ways,
which affected the format of stored settings. Arrgh. So now
settings.c contains yet more painful warts and I'm _really_ starting
to think it's about time we designed a new set of human-usable
config keywords and retired this lot to the status of Unpleasant
Backwards-Compatibility Relic.

[originally from svn r2735]