Move set_filename() calls outside of parse_file()

Remove the boolean parameter from parse_file; the code is more readable
by having an explicit call to set_filename() where necessary, rather
than a boolean parameter.

Signed-off-by: Alberto Mardegan <mardy@users.sourceforge.net>
Add a Qt main window

This is just an empty window with a File menu and a few items.
It shows how to hook up functions to menu actions.

Signed-off-by: Alberto Mardegan <mardy@users.sourceforge.net>
Separate Gtk related code from core logic: divelist

This is simplistic & brute force: any function that touches Gtk related
data structures is moved to divelist-gtk.c, everything else stays in
divelist.c.

Header files have been adjusted so that this still compiles and appears to
work. More thought is needed to truly abstract this out, but this seems to
be a good point to commit this change.

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