added automatic labeling for the axes (up to 4 categories)
added automatic labeling for the axes (up to 4 categories)
added optional labeling of the axes with the ticks instead of ext label for more robusteness, added an optional rotation parameter
added optional labeling of the axes with the ticks instead of ext label for more robusteness, added an optional rotation parameter
corrected some potential 2to3 pitfalls, but it still need more control