#25 non-printable area included in sizes

[Justin Berstler]

Apparently, the current layout code is based on the
entire area of the page - including the non-printable
portion needed by the printer. The problem arrises
when printing on std letter paper in 4x6 photo sizes
where two photos are laid out on the same page - one
horizontally and one vertically. Such a layout
requires all 11 inches of the page which are not
necessarily printable.

The solution is to include code to impose margin around
all edges of the page while laying out photos.