v3.9.0

• follow-the-label column choice, where if a label is selected for plotting from the first file, it will automagically shift to find the matching label in subsequent files, even if the column containing the quantity has changed
• implemented vtk reader capable of reading snapshots from Shamrock code
• apply transparency to smoothed particle plot only if adaptive smoothing used
• plot colour bar by default when particle colouring by quantity is used
• can read velocity array from fits header for position-position-velocity cubes
• bug fix with first page being white with smoothed particle plots on black background
• bug fix finding .comp file if underscore in the directory name