Revamp gnuplot plotting to generate better output

Using the pdfcairo terminal for generating fluid flow plots in gnuplot
using raw paraview-generated CSV exports generates high quality results.
Sadly the resulting files are both unoptimized and quite big which leads
to both large and unperformant documents (i.e. some PDF readers even crash)

As an alternative this new gnuplot structure generates the fluid plot
itself using the pngcairo terminal and includes the resulting
high-resolution PNG image into a normal pdfcairo plot. This works out
quite well.

As a side benefit the plot scripts are now much easier to maintain.

1 files changed, 0 insertions, 0 deletions

diff --git a/img/tmp/cylinder2d_single_refinement_60s.png b/img/tmp/cylinder2d_single_refinement_60s.png
new file mode 100644
index 0000000..847c215
--- /dev/null
+++ b/img/tmp/cylinder2d_single_refinement_60s.png