Interim checkin: basic categorical X coordinates working
Basic axis labelling for discrete data
Ordering of categorical data (by attribute and by metadata)
Jitter for categorical plots
Basic categorical bar charts working, plus two-stage scalers
Fix undefined object error
plotDataHttpProvider fixes
Correct fix for undefined object error
First working hierarchical categorical bar charts

Looks pretty good: X-assignment, Y-aggregation, paint assignment all
OK.  Need to work on ordering and axis labelling.
Ordering by metadata/attribute (hierarchical classes)
Grouping for categorical data
Very simple box plots
Fix some problems with plot-data