Improved sparklines

Rather than connect all data points with a single line, as we do currently in our sparklines, we could do the following:

1. Plot each datapoint as a single pixel
2. Draw a single line, smoothed over a small sliding window of N data points (N is 4, perhaps)

There are two consequences of this:

a) it will allow us to have multiple data points for a single x value (which will be useful later if, for example, we change the x axis to be revision, rather than time, thereby allowing for multiple data points for a single x-value
b) it may make it easier to read the underlying trend and distill out the noisiness of the data