Color print: Show SAC lines in a color different from white

Also make the profile border color the same as the depth grid color.

Fixes #97

Signed-off-by: Lubomir I. Ivanov <neolit123@gmail.com>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
Print dialog: Fix inaccessible controls on Windows

The window which holds the custom print options tab appears to have
unchangeable dimensions on Windows OS (unless hacked in some way).
This makes the sliders in the custom tab not accessible unless
we add the entire dialog into a GtkScrolledWindow and return that
for the "create-custom-widget" event.

The patch also makes the contents of the "Layout Options" frame
packed vertically (with a GtkVBox) instead of horizontally, so that
the entire tab contents are "mostly" scrollable vertically instead
of horizontally.

Signed-off-by: Lubomir I. Ivanov <neolit123@gmail.com>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>