Is your feature request related to a problem? Please describe.
Using the slopes to build theres often situation where a corner slope would look much better than a full block.

Describe the solution you'd like
Either a new corner block or the existing one can work like stairs and create a corner automatically.

I'll look into it sometime soon. I'm not yet sure of how much work it would be.

A cheaty way to do it would be to just copy the model and rotate it 90* so that it intersects the other side. It would work but look strange for transparent blocks