Patch for the mswrite plugin

The mswrite plugin of the actual version of AbiWord isn't really workable.

I fixed several bugs, added character conversion and support for page
properties which makes imported Write files look now as they did in Write
before.

Unfortunately, I had to give up my plan to add support for embedded
pictures, because there seems to be no plugin documentation or how to
pass picture information to the document during import. (I tried to use
the bmp plugin, but I wasn't successful. It seemed that I cannot simply call
IE_ImpGraphic_BMP::importGraphic() which could do the necessary work
otherwise.)

If there is any plugin documentation or any other helpful resource, please
let me know. (Especially if it *is* possible to use the bmp plugin.)

Ingo