Better plane building with Ctrl+Shift

Plane building as it currently exists is great for cubes, but less helpful for non-cubes, and I think it can be improved.

To set a baseline a plane with cubes works by starting the plane at whatever block you were looking at when you started pressing Ctrl, and creates a flat plane of cubes such that the furthest corner of the plane aligns with your mouse. We already know how this looks.

For edge slope blocks, and this is all edge slope blocks not just the basic one, so it includes the longer slopes I believe it should create alternating upside-down and right-side-up slopes such that it creates an angled wall. The angle of the wall should be set by the orientation of the slope block when the plane was started, and would look something like this:

And for corner blocks, it would alternate between being upside-down and right-side-up like with the edge slopes, but it will also alternate with the corner block's inverse corner. Again the angle of the slope would be determined by the orientation of the initial block, and this would work with all corner slope blocks, not just the basic ones, though it would be alternating between the 4 matching different corner slope blocks for long corner slopes. The actual size of a corner slope plane would be the biggest plane that can fit within a cube made by using the initial block as one corner and the focal point for the opposite corner. For regular corner slopes in a 2.5x2.5x2.5 cube though it would look like this:

The above does unfortunately create a double thick wall though so I think that it is also worth, potentially adding squished octahedrons(inverted corner blocks where the cutout is on both opposite corners) like the below so you can make corner slopes that are flat on both sides that are only 1 block wide and therefor can line up with slope planes at its edges and basic planes at its corners.

All in all the changes should make it much easier and faster to make more interesting hull shapes. At least in creative mode, but potentially in survival mode as well if you let us place unwelded blocks in planes like that as well :)