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.
Amber makes some pretty good converters you might find interesting, some are free.