PSC

Copperbox revision 1378.

More work on sparklines. I've made the length of the spark line depend on the word_length attribute rather than the number of points. The number of points wouldn't be very good for many examples in Edward Tufte's Beautiful Evidence, word length still has correspondence with the idea that a sparkline is an in-text dataword.

I'll look at plotting multiple lines soon, this will mean some revision of the SparkLineProps data type.