dpr.to_objfile( file_name, simplified )
if simplified is true, then we only export a simplified mesh made
of the junction graph. Otherwise we export one face per cell, with
the vertices being the points along the cell contour.

Rework the whole code for the upcoming publication.

See merge request !9

I tried to group all the texts in one single graphic object, but it
does not work. 'text' create one text object per position whatever
you do.
So the text plotting routines are still slow.

Courtesy of N. Dray, L. Bally-Cuif lab.

We plot all ellipses as single patch, but this time we color the
vertices. A bit different, but still very instructive. It also turns
out it works very well. Also simplifies and shortens the code.

We now plot the cell many contours as a single patch object relying
on the special low-level syntax of patch.

We want to trim the fat.

The goal is to be able to plot the tissue with one face per cell, to
have a simplified representation of the cells on the tissue with e.g.:
>> patch( 'Faces', F, 'Vertices', V, 'FaceColor', 'g' )

Brute force, thanks to the power of linear scattered interpolant.

We need to check that an argument is not empty before checking whether
it is nan.