Travis may not catch issues that would arise on recent macs

[ludomal]

Travis may not catch issues that would arise on recent macs.

On macOS 10.13 and AppleClang 10, the execution of spdemo would abort with Trap 6 (#116), but Travis and AppleClang 9 would not.

Originally posted by @dennisguse in #116 (comment)

[dennisguse]

Nice to have?
I would rather wait for the next release of TravisCI than investing time on this.
It is kind of annoying to use old compilers for continuous integration, but we still have some larger issues (e.g., documentation) to tackle first.

What do you think?

[ludomal]

This was more like a do not forget rather that a should fix. Hopefully the next release of Travis CI will be more representative of the latest MacOS.

We should definitely spend our energy somewhere else.