plotstats: compute t-tests even if we do not plot boxplots
plotstats: compute t-tests even if we do not plot boxplots

Signed-off-by: Jean-Yves Tinevez <e56a6ee37544ca2467315a0f3163c8180fa84354@pasteur.fr>

tinevez/jyt-matlab,tinevez/jyt-matlab,tinevez/jyt-matlab,tinevez/jyt-matlab,tinevez/jyt-matlab