Improve Windows compatibility.

[bdice]

With help from @lmcinnes, I specialized the ripser class in C++ to fix build problems with Windows.

This PR uses MSVC instead of MINGW on Appveyor, enhancing compatibility with mainstream Windows. This should also make it possible to enable Windows builds via conda-forge.

[codecov]

Codecov Report

Merging #82 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master      #82   +/-   ##
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  Coverage   92.41%   92.41%           
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  Files           3        3           
  Lines         145      145           
  Branches       24       24           
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  Hits          134      134           
  Misses          9        9           
  Partials        2        2

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[lmcinnes]

Looks good to me.

[ctralie]

This is so great, thank you so much @bdice and @lmcinnes. If this works, it will save me tons of time re-implementing a numba version of ripser.

I am noticing this problem in the CI however:

c:\projects\ripser-py\ripser\ripser.cpp(885): error C2039: 'back_inserter': is not a member of 'std'

I'm surprised by this; why wouldn't this be imported in the std library? Is there a similar function that does the same thing?

[bdice]

@ctralie Ah! I didn't see this on my local Windows build for some reason -- might be a difference in Visual Studio versions? As suggested in erengy/anitomy#2, I added #include <iterator>. I think this might fix it, we'll wait for CI to see.