#187 VobSub import does not honor origin

[Jeppe Oland]

When cropping widescreen videos (to not compress the letterbox area), the original subtitle layout is no longer correct.

The IDX file supports specifying an origin.
For example:
# Origin, relative to the upper-left corner, can be overloaded by aligment
org: 0, 58

MP4Box seems to ignore this value, whereas mkvmerge correctly offsets the subtitle.

[Jeppe Oland]

FWIW, I found a workaround.
Applying the inverse offset to the size accomplishes the same thing.

In the previous example, the 720x480 frame size changes to:
# Original frame size
size: 720x422

[Jean Le Feuvre]

could you provide a sample vobsub test file for that ?