scipy misc/special

[gregoryng]

https://github.com/cgrima/subradar/blob/4d44e74a6ce3741e3f63a2ae275f6265bd788894/iem.py#L10

This is causing some problems for regression testing in SDS, would you mind if we support both new and old scipy versions like this:

try:
    from scipy.misc import factorial
except ImportError:
    from scipy.special import factorial

[gregoryng]

Actually this isn't causing a huge problem for testing, so it's kind of up to you whether to use it. The library would be slightly more flexible, but the code would not look as clean.