Natural measurement system

pqs implementation of a Natural measurements system.

semantics of operations

In the natural units system it is planned to use a different semantic again making all quantities coherent using the mechanisms experimented with in the quan library as shown here:

https://github.com/kwikius/quan-trunk/blob/master/quan_matters/examples/make_coherent.cpp
https://github.com/kwikius/quan-trunk/blob/master/quan/fixed_quantity/operations/make_coherent.hpp
https://github.com/kwikius/quan-trunk/blob/master/quan/meta/log10_ratio.hpp
https://github.com/kwikius/quan-trunk/blob/master/quan_matters/examples/log10_Incoherent_units_idea.cpp