Property definitions

gtk $ GdkColor :: new
	new (color_name: String) import String.to_cstring `{
		GdkColor *color = malloc(sizeof(GdkColor));
		gdk_color_parse(String_to_cstring(color_name), color);
		return color;
	`}
lib/gtk/v3_4/gtk_core.nit:1100,2--1104,3