This patch adds a new feature to the 3D-Print Toolbox enabling a per-object rotation transform before exporting, as shown in the attached image.
This feature free us to orientate the objects in Blender, irrespective of their print orientation. When developing mechanical parts, for example, we usually want to maintain the whole piece set in their assembled locations.
Of course, we can turn the object in the slicer software. However, in Blender, it eases the iterative workflow and the object goes straight in the print orientation saving some clicks and simplifying the 3d print workflow.
Unfortunately, this patch brings back some code removed some commits ago related to the method merge_object. I don't know another way to rotate the object and maintain all modifiers correctly (e.g. boolean modifiers). Fell free to change it if there's a better way.