exhaustive tests moved to a separate module so that they may be compiled with opemp if available
include guard corrected
include guard for omp.hpp corrected
changes to nt2.compiler.options.cmake reverted
the exhaustive tests for the euler functions use extern.cephes
Merge pull request #773 from MetaScale/exhaustive_module

Exhaustive module
Reimplement nt2::swap

- Remove dependencies on BLAS
- Support sub-table swap
- Potentially optimized in SIMD/threading