prepare-for-gtk3: Remove calls to Gtk::Dialog::set_has_separator() (#7)

Originally in Gtk2, by default, dialogs showed a horizontal separator
between the content area and the action area (buttons).  GParted
explicitly called Gtk::Dialog::set_has_separator(false) for all it's
dialogs to remove the separator.

In Gtk2/Gtkmm2 2.22, separators were deprecated [1].  In Gtk3/Gtkmm3
separators in dialogs were removed altogether, including all the related
APIs [2][3][4].  Therefore remove all calls.

References:
[1] Commit - "Document separator-related api in GtkDialog as deprecated"
    6f6650e6cf

[2] Commit - "Remove separators from dialogs"
    d433a60611

[3] GTK+ 3.0.0 NEWS file
    https://gitlab.gnome.org/GNOME/gtk/blob/3.0.0/NEWS#L779
    "
    Overview of Changed from GTK+ 2.90.6 to 2.90.7
    ==============================================

    * Various deprecated APIs have been removed:
    ...
    - GtkDialog separators, including the GtkDialog::has-separator
      property, including setter/getter, the GTK_DIALOG_NO_SEPARATOR
      flag and the GtkMessageDialog::use-separator style property
    "

[4] Gtkmm 3.0.0 NEWS file
    https://gitlab.gnome.org/GNOME/gtkmm/blob/3.0.0/NEWS#406
    "
    * Dialog:
    - Remove get/set_has_separator() and property.
    - Constructors: Remove use_separator parameters.
    "

Closes #7 - Port to Gtk3

src/DialogFeatures.cc

@@ -27,7 +27,6 @@ namespace GParted
 DialogFeatures::DialogFeatures() 
 {
 	set_title( _("File System Support") ) ;
-	set_has_separator( false ) ;
 	//Set minimum dialog height so it fits on an 800x600 screen
 	set_size_request( -1, 500 ) ;
 

src/DialogManageFlags.cc

@@ -30,7 +30,6 @@ DialogManageFlags::DialogManageFlags( const Partition & partition, std::map<Glib
 	any_change = false ;
 
 	set_title( String::ucompose( _("Manage flags on %1"), partition .get_path() ) );
-	set_has_separator( false ) ;
 	set_resizable( false ) ;
 
 	Glib::ustring str_temp = "<span weight=\"bold\" size=\"larger\">" ;

src/DialogPasswordEntry.cc

@@ -29,7 +29,6 @@ namespace GParted
 DialogPasswordEntry::DialogPasswordEntry( const Partition & partition )
 {
 	this->set_resizable( false );
-	this->set_has_separator( false );
 	this->set_size_request( 400, -1 );
 
 	/* TO TRANSLATORS: dialog title, looks like   LUKS Passphrase /dev/sda1 */

src/Dialog_Base_Partition.cc

@@ -23,7 +23,6 @@ namespace GParted
 	
 Dialog_Base_Partition::Dialog_Base_Partition()
 {
-	this ->set_has_separator( false ) ;
 	frame_resizer_base = NULL;
 	GRIP = false ;
 	this ->fixed_start = false ;

src/Dialog_Disklabel.cc

@@ -28,7 +28,6 @@ Dialog_Disklabel::Dialog_Disklabel( const Device & device )
 
 	/*TO TRANSLATORS: dialogtitle, looks like Create partition table on /dev/hda */
 	this ->set_title( String::ucompose( _("Create partition table on %1"), device_path ) );
-	this ->set_has_separator( false ) ;
 	this ->set_resizable( false );
 
 	{

src/Dialog_FileSystem_Label.cc

@@ -28,7 +28,6 @@ namespace GParted
 Dialog_FileSystem_Label::Dialog_FileSystem_Label( const Partition & partition )
 {
 	this ->set_resizable( false ) ;
-	this ->set_has_separator( false ) ;
 	this->set_size_request( 400, -1 );
 
 	/* TO TRANSLATORS: dialog title, looks like   Set file system label on /dev/hda3 */

src/Dialog_Partition_Info.cc

@@ -31,7 +31,6 @@ namespace GParted
 
 Dialog_Partition_Info::Dialog_Partition_Info( const Partition & partition ) : partition( partition )
 {
-	this ->set_has_separator( false ) ;
 	// Set minimum dialog height so it fits on an 800x600 screen without too much
 	// whitespace (~500 px max for GNOME desktop).  Allow extra space if have any
 	// messages or for LVM2 PV or LUKS encryption.

src/Dialog_Partition_Name.cc

@@ -28,7 +28,6 @@ namespace GParted
 Dialog_Partition_Name::Dialog_Partition_Name( const Partition & partition, int max_length )
 {
 	this->set_resizable( false );
-	this->set_has_separator( false );
 	this->set_size_request( 400, -1 );
 
 	/* TO TRANSLATORS: dialog title, looks like   Set partition name on /dev/hda3 */

src/Dialog_Progress.cc

@@ -29,7 +29,6 @@ namespace GParted
 
 Dialog_Progress::Dialog_Progress( const std::vector<Operation *> & operations )
 {
-	this ->set_has_separator( false ) ;
 	this ->set_title( _("Applying pending operations") ) ;
 	this ->operations = operations ;
 	succes = true ;