PATCH - PD_Style::isList()

Hi,

while working at the new gtk combos i noticed a problem related to
PD_Style::isList().
It returns TRUE even when "list-style:None" is set. I'm proposing the
attached (very simple) patch to the list because of the feature freeze
and because this is very central in abiword. Caching of the list
attribute is also removed because the cache is never reset, so it
might lead to inconsistencies when changing the style (i read through
the source code, this should not be called frequently anyways).

Please approve, then i can remove some dirty hacks from the gtk style
combo and fix my remaining issues with it.

Thanks,
- Rob