move fma4/altivec code for fma to correct_fma and make fma use correct_fma for those extensions. Also make correct_fma use fma for integers.  Fix #452
make native include logical
make functions include as_logical.hpp instead of logical.hpp + move logical_ hierarchy to category.hpp
bad file in details/logical.hpp
pass X by reference in integration, use result_of instead of typeof -- related to #460
factoring reduction code for trig functions
adding two trigonometric constants
scalar all must be defined on bool and return a bool
using the new constants in trig reductions
factoring reduction code for trig functions
using the new constants in trig reductions
bad comment in deginrad
constant 1/90
using the constants in reduce functions
 factorizing double simd/scalar trig reduction
 factorizing float simd/scalar trig reduction
 factorizing float/double trig reductions
 static choice at the clipped level instead of run-time if
coorecting /more_cosine.cpp
in order it doesnot enter an infinite loop (bench)
suppresing commented includes in trigo.hpp