Expand Travis-CI scope
Created by: SethMMorton
This is intended to address and close issue #117 (closed).
This PR will take many iterations to get correct, so I have prefixed the title with WIP to indicate it is a work-in-progress. I will remove WIP when I think it is read to merge.
Testing against multiple
- Testing against multiple Python versions
- Testing on Linux
- Testing on macos
- Testing on Windows
On Linux, testing against both clang and GCC (not sure if this is needed?)