To do: Jan 24

[dicook]

• [x] Figure 16 should probably use a sequential colour scale, and different line types, to indicate increasing nonlinearity. (Patrick: need to check whether the colour pal looks good)
• [x] Fig 18 should have a diverging scale, to indicate butterfly is middle, and the others are on each side of this. (Patrick: also need to check whether the colour pal looks good)