updated copyright on is_nan.hpp
removed altivec implemetation of is_ord: there is no altivec intrinsic for is_ord, this was just a less efficient version of the new version in common
added is_unord.hpp to common folder: the neon version of this is no longer mapped to scalar thus eliminating emulation of this function on arm. Added BOOST_FORCEINLINE to scalar is_unord.hpp
added additional unit tests to shift_left.cpp to test the changes made to the arch arm version of this which can now accept both signed and unsigned arguements
removed result type from return value of is_nan.hpp