Gather every module in boost.simd into a base module
Move arithmetic inside boost.simd.base
Move bitwise inside boost.simd.base
Moved boolean to simd.base
Moved ieee to simd.base
Moved operator to simd.base
Moved predicate to simd.base
Move core toolboxes into core.base
Fix toolbox dependencies after base module implementation
Moved type.complex.??? to type.complex.base
Moved arithmetic exhaustive to core.base