Graphs using geometry edges

[picirrottola]

To make graphs, now we need, of course, section planes.

But definition of curves using pick points is tedious and, more important, not enough precise.

So, I suggest to add at least two new feature to define base curve for graph:

1. selection of an existent geometry edge, already present in parts description;
2. addition (and selection) of intersection curves between geometry and section plane;

in this way, it will be possible to draw and export graphs in a very wide number of precisecurves.

Many thanks

    Piero