Doc for is_logical_mask and is_bitwise_logical updated. is_logical_mask now inherites from is_bitwise_logical - an overload must be provided for architectures which logical SIMD types are bitwise_logical but are not represented by all 0 or ~0
Added a terminal_of specialization for expression

terminal_of of an expression<T,R> is computed as the terminal_of
of R. This shortcut was missing for some reasons and forced to
use a inefficient semantic_of+terminal_of combo which has been
corrected in related files.
Add support for tieable modf on tables
use avx blend for cardinality 4 shuffles with pattern (0 or 4,1 or 5,2 or 6,3 or 7)