TexFace complicates the now more popular shading pipeline by having
per-face images, see: T51382 for details.
To keep the ability to select a per-material edit-image
(used with UV-mapping workflow), the material now stores an image
which will be set when changing images in edit-mode.
This is used as a bake-target when not using Cycles too.
Original patch by Jan Diederich, adapted by Pelle Johnsen. Review assistance by Daniel Tavares.
This patch adds an option to export only the selection.