Slic3r - Rotating Face to Bottom

The primary goal of this project would be to implement a solution to issue #3047. This issue is basically about implementing a way for users to select a face and choose it to be the face that connects to the plate. Specifically, after implementing this feature, I expect that a user would be able to click a face (which should be highlighted to make clicking the right face easy) on an object and then click menu button to rotate that face to bottom of the model. If there is a part of the object below the plate after the rotation, it should either error or push the model up until it is no longer intersecting the plate (I’m not sure which is more intuitive).