The plotting functions of the package draw with base R graphics, which
produce no object to keep. The wrappers summarizeSCI() therefore store
each plot as a sci_plot: the instructions to draw it, together with the
numbers it shows. Printing a sci_plot draws it on the current device, and
save_plot() draws it into a file of the requested size, so that the
layout is always worked out for the size it is drawn at.