[Yt-dev] hop improvements

[Matthew Turk]

Hi guys,

Britton and I worked on some improvements to hop today.  Specifically,
changing the means of accessing attributes from *copying* to
*in-place* access.  This should cut down on the memory substantially,
but I believe there are still places that it could be improved.
Specifically, I think a consolidation of the tags & iHop attributes
could improve things.

I've placed the patch at paste #97, and you additionally need:

http://yt.enzotools.org/files/hop_numpy.h

If y'all get a chance to look at it, see if it cuts down on memory
usage at all, that'd be awesome.  We're currently running a bunch of
tests.  If it works out, we're moving to this over the old method.

-Matt