feature request - texel density

[kyrahabattoir]

When using the "blender unwrap mode" the object face should have a uniform texel density (pixel/world meter) in width & height, however it is currently not possible to get it, set it (which would be very useful to quickly apply the same density between multiple surfaces), or to rotate UVs while preserving X/Y density, on non-square textures.

I realize rotation might be an absolute pain, but having it, even just for 90° increments would be immensely useful already.