We should set up test services, Travis CI, AppVeyor, maybe others so every commit and PR gets the tests run on it in a number of configurations. Travis workers are Ubuntu 12.04 VM's, AppVeyor workers are Windows server VM's (2012 R2 I think) on Azure. AppVeyor has several versions of MSVC installed on the workers, hopefully including the ones preferred by cpython upstream. We can set up build matrices for different setups - conventional Linux build, cross-compile from Linux (ppa:tobydox/mingw has MinGW-w64 GCC 4.8.x snapshot for Ubuntu 12.04, does not include gfortran for numpy though), conventional MSVC build on AppVeyor, MSYS2 build on AppVeyor (need to run setup non-interactively, should be doable).

Travis CI also allows multi-os builds on Mac too, but they have limited capacity and we have to ask for it. They're not accepting new repositories for Mac builds right now.

This only applies to the branches we're working in, don't need to put these .yml test configuration files in the pristine upstream branches.