fix: memory leak when the load default palette button is repeatedly p…

…ressed (synfig#2633)

-freed the memory of the tables children from the previous iteration when the refresh function is called.

synfig-studio/src/gui/modules/mod_palette/dock_paledit.cpp

@@ -389,6 +389,11 @@ Dock_PalEdit::refresh()
 {
 	const int width(12);
 
+	// Free table children from memory
+	std::vector<Widget*> children = table.get_children();
+	for(Widget* child : children)
+		delete child;
+
 	// Clear the table
 	table.foreach(sigc::mem_fun(table,&Gtk::Table::remove));