- Install pandoc2 in travis and decide whether to use it or not in tox.
- A symbolic link is created in tox, due to not being able to make
setenv work like this: `setenv = PATH={toxinidir}:{env:PATH}`
- Install pandoc2 only on pyxx-pandoc2
- Add new inclusion to travis matrix combination
- A build failed with InsecurePlatformWarning on Travis.
