plots results of a post-hoc multiple comparison tests, similar to multcompare of matlab params: m, as returned from multcompare labels, strings for y axes, in order of processing by multcompare markSig: y/n, to mark significance bars plotMode: plot as ANOVA (1, firing on y axis) or as bars (2, bargraph with firing on y axis). urut/aug05 urut/oct06, added bargraphs