Problem: if there is a rotstep, then rotated callouts are not displayed under the good angle.
Reason: the problem is that, if a rotstep is set, then two rotations are applied
instead of one, in drawPage() (in traverse.cpp).
More precisely, firt the submodel is rotated according to the rotstep, line 396 of traverse.cpp
Then, the rotstep is cleared (line 403), and the submodel is displayed (line 417). This applies
a second rotation, corresponding to the default view angle.
Solution: do not rotate the submodel according to the rotstep, and keep the rotstep for line 417.
File bug3.mpd is an example showing the bug
File bug3_patch.txt is a patch correcting the bug