Before this commit, all VOs had to toggle the option flag themselves,
now command.c does it.
I can't really comprehend why it required every VO to do this manually.
Maybe it was for rejecting the property/option change if the VO didn't
support a specific capability. But then it could have checked the VOCTRL
result. In any case, I don't care, and successfully changing the
property without doing anything (With some VOs) is fine too. Many things
work this way now, and it's simpler overall.
This change will be useful for cleaning up VO option handling.
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