Have you tried Calibre
(free SW converter/reader)? I'm not the expert but I believe you can convert all those formats to Epub and Calibre will do a batch convert.
Not exactly what you're looking for but may suffice. There is also a relatively new program being worked by one of MR's members called Sigil
. It's an Epub editor and is already pretty good. This may be of interest to you.
makes some pretty good converters you might find interesting, some are free.