Add spot heights to cut/fill analysis

[philipbelesky]

This a bit premature given #44 hasn't landed, but I'm waiting on VS to update so here is the idea:

The MeshCompareComponent would take an optional list of points. These would be projected on to the mesh, in a similar manner to the cropping tool. and also passed to the main component. The main component then would compare the difference in elevation between the comparison mesh and the live mesh. To visualise this it would draw a line between the two and/or provide a numeric read out.

The idea/value here is based on the following:

• The visualisation mesh is somewhat imprecise as it doesn't explicitly note what the change in elevation is
• Sometimes you may be specifically developing a change to the landform that raises it to a specific height which this enables
• It could be valuable to hide the live mesh and use a grid of these depth points as a more 3-dimensional 'xray' into the landform changes (particularly if using an AR setup)

[mariuszhermansdorfer]

Added label display as an option. It works with the CutFilland Elevation analysis modes. Users can control the density of the spot markers or turn them off completely with the Label spacing slider.

Text size should adapt to the chosen spacing. Display precision changes with drawing units too.

Working with the CutFill option allows us to focus only on the relevant area:

Or display the exact elevation differences between the provided mesh and the current state of our model:

Is this what you envisioned @philipbelesky?