Polar plot improvement

Hello,
great usefull tool. It would be great if the polar plot can be improved by adding a tangent condition at the end of the lines.
The orc data for upwind is cut at the vmg. That is the 1st point of the upwind data is the VMG. This by definition has a gradient of zero (delta Vmf/delta TWA).
By adding this simple condition the polar graph would be greatly improved.
See red lines below as an example. The same applies for the downwing VMG


Start by locating the polar plot rendering and the ORC upwind and downwind VMG data handling. Check how the first VMG points are currently connected, then verify the plot uses a zero-gradient tangent condition at both ends and compare the result with the attached example.

Written by the indexing model from the issue text.