Remove all `enum'-typed variables from the Config structure.

Remove all `enum'-typed variables from the Config structure.
Everything in there which is integral is now an actual int, which
means my forthcoming revamp of the config box will be able to work
with `int *' pointers without fear of doom.

git-svn-id: svn://svn.tartarus.org/sgt/putty@2733 cda61777-01e9-0310-a592-d414129be87e