Moved the function attribute macros from the static_fft.hpp header into the details/missing_functionality.hpp header.
Changed/fixed the BOOST_FASTCALL macro for GCC/Clang not to include the hot attribute. Added separate BOOST_HOT and BOOST_COLD macros.
Added a workaround for bad code/twiddle factor generation by Clang 3.3 when fast-math is enabled.