legend_ncolumn > 2 and percentage indicators

[sgnoohc]

Third column has some issues.

[aminnj]

See

plottery/utils.py

Lines 216 to 218 in e17418f

	# note, we can't support more than 2 columns because
	# ROOT won't give us an easy way to get the relative sizes
	# of the columns (we need to know the text sizes) :(

:(

Right now, we assume the columns have the same width, but this is not the case for you. Your "WWW" pushes the second column further.