Add a Percentage Slope visualisation of TIN

[RobinPREST]

In 3D analyst, one can view elevation, edges,  but also Slope as displayed below : (Face slope with graduated color ramp).



For the moment Slope is expressed in Degrees by default. It would be useful to add an option to have the same visualisation but in percentage.



For the moment, the only way to see it is to use the "TIN triangles" tool, but it's not interactive like with the renderer.