Positive and negative values in preset

[flakorama]

I can't seem to iterate correctly though negatives and positives values when I'm building presets. It looks like the values always move forward (i.e. I can't move from a positive angle to a negative one, the preset API always put the negative one first). It is a severe issue when I'm building extensible arms with multiple cylinders and hinges, because I need some parts to be facing the opposite direction and decrease in angle or position. Please fix.