Enable and fix the previously untested GtkOptionGtkUIItem::PLOTSIZE.
This has the potentially unfortunate side effect that integer range
options are assumed to be plot sizes. That's correct for now, but
if some report comes along that needs an integer range option for
something else it will have to be differentiated.
This change was inspired by mildred's #PR1247 and uses the new
GncReportCombo to allow selection of 'Saved Invoice reports' when the
invoice print button is used or when printing multiple invoices.
This change presents a dialog with the default for the report combo set
to the properties setting. This dialog has a timeout which is
adjustable under properties and will stop if a key is pressed or combo
popped so that a different report template can be selected and used.
There is also an 'OK' button that stops the time out and prints and a
'Cancel' button which cancels the print.
This commit changes the preference in Business->'Report for Printing'
to be saved as a book property and allow the selection of any Invoice
Report to be used as the default.
The compiler complains that there's no matching
gnc_register_number_range_option for GncOptionDB*, which without this
commit is true because the explicit templates are for GncOptionDBPtr&.
Note that the original template definition is for GncOptionDB* and
that the header-defined inlines that take GncOptionDBPtr& call the
GncOptionDB* version.
