This addresses the following issue: by default, when you export in a non-Blender orientation
(matching your target import app), your imported root objects have additional rotation,
since correction matrix is applied to object transform.

This patch addresses this by actually baking the correction matrix at data level, when possible
(currently only works for meshes).

Note this makes spaces/matrices handling rather complex, so this is considered an experimental
option currently, might break in some cases.

Work based on patch T39251 by Jens Restemeier, thanks.