forked from: corners to Matrix3D

multipart project 2
part 4 of, I don't know, like 5

Background:
Okay, so it's really easy to spin a plane in 3D. But what I
really need is to be able to overlay a rectangular
DisplayObject over someting in an image. That is, I need to
find the appropriate Matrix3D given 4 points.

Task:
- generate a Matrix3D given points
- make a UI to to customize this