Make slider labels consistent in print dialog

To make this easier I created a new helper function create_label that
takes printf style arguments. I assumed this would be usable in many
places but ended up finding just one other obvious use for it.

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
Rescale print layout sizes to add to 100%

While it makes sense for the program to have a 7.5% fixed header, from a
user perspectice this is just odd. So instead we now have the notes,
profile and tank data sizes add up to 100% and scale the information when
it is combined with the header.

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>