Hook in BarSeries

Introduces the BarSeries as a new common base class between Row and
Columns, and plugs it in.

Currently, this does not hold any functionality of its own.
Separate row/cols in css classes

Both RowSeries and ColumnSeries were using the same classValues. Here,
we create a new one for each Row and Column, keeping BarClass for
BarSeries.
Pull common functionality up

Almost all of the code is shared, so could be pulled up.

For now, there are some slightly messy instances where some methods are
different for cols and rows. I'll be cleaning these up in future commits