WIP: g++ 8 / arch tests

I was struggeling with gcc 8 recently. With the lcg version (8.1.0) i didn't manage to build SOA, with (8.2.0 current arch linux version) there's a change necessary. Which … I'm not sure it's a compiler error. Anyway, the bodge and another platform for testing are here. And some reworking of the CMakeLists (I was annoyed I can't set the c++ standard from the command line).

This is clearly not in a mergable shape, it's just to publish the branch.