update to 2014 CODATA recommended values

[e-kwsm]

2006 CODATA recommended values are used.

Significant changes:

• units/include/boost/units/systems/si/codata/electron_constants.hpp

  Lines 75 to 76 in d67f8e7

  	/// electron-nuclear magneton moment ratio
  	BOOST_UNITS_PHYSICAL_CONSTANT(mu_e_over_mu_N,quantity<dimensionless>,-183.28197092*dimensionless(),8.0e-7*dimensionless());

  
  became 10x bigger (this should have been −1838.281970292)

• units/include/boost/units/systems/si/codata/triton_constants.hpp

  Lines 63 to 68 in d67f8e7

  	/// triton-electron magnetic moment ratio
  	BOOST_UNITS_PHYSICAL_CONSTANT(mu_t_over_mu_e,quantity<dimensionless>,-1.620514423e-3*dimensionless(),2.1e-11*dimensionless());
  	/// triton-proton magnetic moment ratio
  	BOOST_UNITS_PHYSICAL_CONSTANT(mu_t_over_mu_p,quantity<dimensionless>,1.066639908*dimensionless(),1.0e-8*dimensionless());
  	/// triton-neutron magnetic moment ratio
  	BOOST_UNITS_PHYSICAL_CONSTANT(mu_t_over_mu_n,quantity<dimensionless>,-1.55718553*dimensionless(),3.7e-7*dimensionless());

  
  removed (since CODATA 2010); users can obtain by themselves

[jhunold]

The update of mu_e_over_mu_Nis necessary. Simply removing the other three constants is not an option. We have to deprecate them first.

[e-kwsm]

Simply removing the other three constants is not an option. We have to deprecate them first.

I updated the values.

BTW what is the standard way to deprecate a variable in boost? Other libraries use (wrappers of):

• [[deprecated]] attribute (C++14): Boost.Atomic, Boost.Unordered
• __attribute__((deprecated)) (GCC and Clang extension): Boost.Atomic, Boost.Unordered
• __declspec(deprecated) (MSVC extension): Boost.Asio, Boost.Atomic, Boost.Unordered
• #pragma message: Boost.Accumulators
• #warning: Boost.Accumulators

[jhunold]

We cannot use [[deprecated]]right now because this breaks C++03 compatibility. Which I won't do now.
The last two are only useful (and currently used) for deprecation of whole headers. So a macro abstracting the compiler extensions would be nice. Thinking about it.

[e-kwsm]

2018 CODATA recommended values are released. I will close this when I create a new PR for 2018.