import freud fails without scipy installed

[Matthew Spellings]

Due at least to the import in sphericalharmonicorderparameters.py. Elsewhere we haven't been enforcing the requirement just to import freud.

[Eric Harper]

is this a fail off

from freud import *

or something else? I thought Ben or Irrgang used scipy for something? It shouldn't be hard to make this not be an issue for general freud, although if nothing else uses it, we shouldn't have it if there's another way to do it.

[Matthew Spellings]

It could be made such that sphericalharmonicorderparameters is not imported automatically when importing freud, or it could be imported just before being used in sphericalharmonicorderparameters, or it could be put inside a try/catch block and error out when sphericalharmonicorderparameters uses it.

[Eric Harper]

hmmm...well, I don't necessarily see why scipy is more arduous a requirement than numpy, but at the same time we don't want to have an ever expanding list of requirements. I don't like not auto importing everything with the * import, so I guess I would go with the try/catch

[Matthew Spellings]

Well, we don't require scipy to be present for the optional convex hull functionality in freud.shape and acquiring it is not necessarily as simple as a pip install scipy --user since it has many compiled bits, so continuing to not require it seems reasonable to me.

[Richmond Newman]

Chrisy, isn't this import no longer needed? Assigning problem to you.

[Chrisy Du]

I forgot to comment on this, but scipy dependency in the shop module is no longer needed