Fixed plotting of errorbars using custom Gviz:
o Mean+CI visualization: SD is now computed in fast, vectorized form rather than using apply() which is basically a for loop
o Instead of drawing one polygon, we draw multiple ones bounded at any missing locations. This fixes the ugly rendering resulting from polygons with NAs in the middle of the trendline.
o Removed some message statements.
o Corrected the property which resulted in the message regarding rownames of a short variable, each time Gviz made a data.frame. The culprit was the 'fill' variable which was named.