[Feature] Vertex colouring for wind mechanics

[heinermann]

Vertex colouring branches and leaves so that a shader can cause them to move "with the wind" or some other mechanism.

This feature is in TreeIt (pictured), which generates trees similarly.

[JekSun97]

@heinermann Thanks for the idea! This feature has already been requested, I will try to add a wind system as soon as I fix critical issues in the plugin