Enhanced mode examples

[Tait <gnu...@t4...>]

This just came up on IRC:
http://gnuplot.sourceforge.net/demo_4.2/histograms.html appears to be
using enhanced mode PNG, which causes the "Soviet_Union" column header
to be interpreted to mean the U should be subscripted. The "set key
autotitle columnhead" should probably be changed to "set key autotitle
columnhead noenhanced".

Tait