Exblas

• introduces exact and reproducible dot product, blas1 and blas2 functions
• adds vcl dependence, as well as dependence on avx and fma vector instruction set
• we are now entirely using c++11 standard, thus, we no longer depend on the outdated c++03 support from JSON
• adds msvc (Windows) support
• in diag and src projects clear up includes to only the dg/algorithm.h and geometries/geometries.h headers
• replace old average routines by a superior class
• improves and structures our tag dispatch system (we are ready for parameter packs)
• makes the distinction between level 1 and 3 clearer by moving relevant files to either the backend or the geometry folder