The implementation in the viewer of the local wind eddies was too closely coupled to that of the Classic Clouds, so that when the clouds were removed in v2.8 the local wind eddies were broken.

This change removes that coupling (along with a few vestigial bits of the classic clouds) and restores the wind eddies.

It turned out that there was also some debug code for visualizing the wind, so I attached that to the Develop>Render Metadata menu (Wind Vectors), adjusting it so that it displays the vectors 25 meters above the avatar (attaching screenshots to the jira issue).  Thanks are due to Runitai Linden for help with this part.

Tested with particles that are sensitive to wind, and the excellent demonstration site linked in the jira issue.