GUI: functional map loading selection

14/07/2014
-added load_decks () and manzana.determine_coordinates_in_grid

-added "load map" interface to main menu, it lists aviable folders in
maps/ships (they contain the diferent maps) and loads all the maps in
the
selected folder into STI by using load_decks()

-started manzana.determine_coordinates_in_grid ()

-added deck_loaded variable to determine if there is a map is loaded, if
it is then the map will start updating and drawing

-added loop to update all decks , draw all decks and resize them, needs
optimizing and cleaning up

-broke: function draw_grid (map)