Automatically calculates the plot height from chunk options and volker options.
.knit_plot(pl)
Character string containing a html image tag, including the base64 encoded image.
A ggplot object with vlkr_options. The vlk_options are added by .to_vlkr_plot() and provide information about the number of vertical items (rows) and the maximum.
Presumptions:
a screen resolution of 72dpi
a default plot width of 7 inches = 504px
a default page width of 700px (vignette) or 910px (report)
an optimal bar height of 40px for 910px wide plots. i.e. a ratio of 0.04
an offset of one bar above and one bar below