<listitem> apparently does not need a <para> tag.
Added early support for output to the epub format.
Revert "Added early support for output to the epub format."

This reverts commit f789ca39fe6f1c2462aec39e368d3f71a2752343.
Revert "Revert "Added early support for output to the epub format.""

Added epub stuff back in.

This reverts commit 6f0179f49723812a3df008b68be9870e6c86d5e2.
Revert "<listitem> apparently does not need a <para> tag."

Apparently it does need a para tag.

This reverts commit 2f4fe695d6d1ca5598ce9e79e32e0674a9658963.
Fixed validation errors. No change to appearance.