Mandate C++14?

[pbauman]

GCC 4.8.2 was C++11 feature complete, so any RHEL 7 based system will natively support C++11. GCC 5 was C++14 complete. My experience has been that the supercomputing centers will deploy a GCC installation if requested, so it shouldn't be a problem.

Intel is more dubious. C++11 Status and C++14 Status. Looks like Intel 14+ supports all of the C++11 features we'd want to use and the C++14 auto/decltype feature we'd want.

I think this could be a good move. It would make the code much more readable, I think.