Major bugfix: inc does not lose data anymore.

What have I done in 70b2643e0da8485174480c644ad9785c84f5bff4 ?
Producing scan listings and inc'ing mail are too closely related.
By removing the body component from scan listings, I also had removed
the ability to copy bodies during inc. Hence this commit undos the
changes. (And reintroduces the body component in scan listings. :-( )
The code is too much interweaved!