Print: add UI for a print dialog

PrintOptions is a QWidget class to be used as an
addition to a future print dialog (possibly based on
QPrintDialog). Currently only contains a couple of
radio buttons.

PrintDialog (printdialog.cpp/h) which is a basic QDialog
is currently added for testing only and it holds
an instance of PrintOptions.

Calling File->Print opens this test dialog for now.

Signed-off-by: Lubomir I. Ivanov <neolit123@gmail.com>
Print: add all controls to the print options widget

- adds missing file printoptions.ui
- adds all controls present in the GTK version of the
print dialog custom tab

Signed-off-by: Lubomir I. Ivanov <neolit123@gmail.com>
Print: further adjust the print options widget UI

Makes the controls less cluterred on Ubuntu.

Signed-off-by: Lubomir I. Ivanov <neolit123@gmail.com>
Print: label update on height slider move

The PrintOptions widget has value labels next to the
horizontal sliders. Add slots to update these labels
when a slider moves.

Patch also makes a modification so that the PrintOptions
constructor requires a 'struct options' pointer. If
an options struct is not received we do not set predefined
values and do not connect signals to slots, where
options will be updated immediately.

Signed-off-by: Lubomir I. Ivanov <neolit123@gmail.com>
Print: correct tab order in the options widget

Tab order should begin from the topmost widget and then
descend towards the bottom end of the dialog.

Signed-off-by: Lubomir I. Ivanov <neolit123@gmail.com>
Print: connect all the options widgets to slots

By connecting to slots we always modify values at a previously
set 'struct options' pointer.

Also have the setup of slots and pre-set values in a
separate setup(struct options *) function.

Signed-off-by: Lubomir I. Ivanov <neolit123@gmail.com>