Toolbar Editor: Default to a bigger dialog size (Issue #758)

The dialog is too small because it has too few buttons on the right and it was setup like the column editor.
To deal with it we could either:
- Create a complex setup of boxes.
- Manually set a top-margin for the `Default Order` button.
- Set the rows to homogenous, which I did. The downside of this approach is that it makes the separator huge, so I removed it.

thunar/thunar-toolbar-editor.c

@@ -140,6 +140,7 @@ thunar_toolbar_editor_init (ThunarToolbarEditor *toolbar_editor)
   grid = gtk_grid_new ();
   gtk_grid_set_column_spacing (GTK_GRID (grid), 6);
   gtk_grid_set_row_spacing (GTK_GRID (grid), 6);
+  gtk_grid_set_row_homogeneous (GTK_GRID (grid), TRUE);
   gtk_container_set_border_width (GTK_CONTAINER (grid), 12);
   gtk_container_add (GTK_CONTAINER (frame), grid);
   gtk_widget_show (grid);
@@ -227,14 +228,6 @@ thunar_toolbar_editor_init (ThunarToolbarEditor *toolbar_editor)
   /* next row */
   row++;
 
-  /* create the horiz separator */
-  separator = gtk_separator_new (GTK_ORIENTATION_HORIZONTAL);
-  gtk_grid_attach (GTK_GRID (grid), separator, 1, row, 1, 1);
-  gtk_widget_show (separator);
-
-  /* next row */
-  row++;
-
   /* create the "Use Default" button */
   button = gtk_button_new_with_mnemonic (_("De_fault Order"));
   g_signal_connect_swapped (G_OBJECT (button), "clicked", G_CALLBACK (thunar_toolbar_editor_use_defaults), toolbar_editor);