Update stat_violin.m

[azabicki]

hi, really nice tool to plot my data!

I think i found a small bug while plotting half violins with two groups (colors) per dependent variable. Your comments in the script are predicting to "draw right half if even index" and "left half if odd", which makes sense to plot the first group on the left side. But It actually is the other way around.

For the first group (index=1), the right half is drawn. And for the second the left.

Here I simply changed the order of drawing half's. Now the left half is drawn first.