Differentiate between intensify=xy (the old default) and intensify=y

The intensify= option can now colour the cells based on global min/max
across all columns (=xy) or just the current column (=y).  Theoretically the
current row (=x) would also be meaningful, but gviz doesn't support that, so
we won't try to do it right now, and just throw a helpful error instead.
1 file changed