provide support for the complex library

[kif]

available since C99... may be valid only after Python2 is dropped on
Windows.

[scoder]

Please add a little test anyway. You can add it to the windows_bugs.txt file to exclude it in MSVC for now (preferably with a comment why it's excluded).

[scoder]

Ping! :)
A test would be helpful to get this merged.

[kif]

Arg, I forgot about it.

[kif]

There is test that works for me ... not sure it works everywhere. let's wait for Travis' point of view

[kif]

Just a question: How do you prevent the test to use the C++ backend ?

[scoder]

Sorry for the silence. There is a tag no-cpp for this (had to look it up myself, found it in runtests.py).

[leofang]

Can this PR be merged? Having access to complex is helpful to scientific computing!

[kif]

That was my original idea ...

[robertwb]

This looks fine to me--doesn't change the default behavior and lets the user cimport rather than declare all of these methods, and the test looks fine as well. Thanks.