Scatterplot matrix

'chart-types-splom': () => ({
  rows: [], config: {},
  foot: ['every pair of measures as its own scatter', 'read the grid to spot which pairs move together'],
  mount: mountGridCharts({
    rows: book(500), columns: bookCols, columnsPer: 1, chartHeight: 420,
    chartTypeModules: ['splom'],
    charts: [{ type: 'splom', columns: ['price', 'bid', 'ask', 'volume'], title: 'Every measure against every other' }],
  }),
}),