VecGhost and state

[Jed Brown]

Matthew Knepley wrote:
> We should just treat LocalForm as GetArray, and increase the state on
> RestoreLocalForm.

I thought of this, but like the maximum better.  With GetArray, you
don't have a nice way to determine whether the user changed anything, so
the cache needs to be invalidated by default.  When the user does not
modify the array, the state is needlessly increased, hence the goofing
with state in VecEqual.

Increasing the state will work fine of course, but I think using the
maximum is equally safe while making better use of cacheing.  Also, if
the global form has changed, I think we want the local form's state to
increase in GetLocalForm.

Jed

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