[Yt-dev] a few new features added to hg

[Matthew Turk]

Hi Stephen,

Thanks for adding these!

> For a given data_source, like 'sp = pf.h.sphere([0.5]*3, .2)', you can get the volume of the region in your favorite units: 'sp.volume('mpc')'. No units gives it in code units 'sp.volume()'.

This is worthwhile, but I'd like to note that because it's using math
arguments rather than the contained cell arguments, it will be
different from doing:

data_source.quantities["TotalQuantity"]("CellVolume")

(and, also, a lot less verbose.)

> I added yt.extensions.StarAnalysis, which has a class StarFormationRate, which when given a data_source with stars in it, will calculate various star formation rates binned over time.
>
> Let me know if you have any questions! And yes, I should eventually document the StarAnalysis stuff!

This is great!

-Matt