math_fp: Remove unnecessary cast in isnan()/NULL
Use a union in null::foreach() to write the results into a vector

foreach() can now be used in cases where the result vector type does not
implement operator[].
Use null::foreach for 64-bit NEON floating point operations
math_shift: Remove useless code in the 8-bit shift implementation on SSE

A SSE-specific optimization does not need provide a default path for
other architectures -- it should be accessible only from SSE in the
first place.
math_shift: Add static_asserts to catch out of bounds shift amount
math_shift: Optimize more cases with compile-time shift amount
doc: Use proper Doxygen tags where needed
memory: Remove store_u()

Unaligned stores have extremely limited potential to be used, since:
 * In almost all cases it's possible to modify data structures so that
only unaligned load support is needed
 * Unaligned stores are always much slower than unaligned loads.

Therefore, it doesn't make much sense to support it.
memory: Reduce code duplication

Most of the time we can defer to the generic initialization version
instead of immediately using architecture-specific functionality.
shuffle: Move shuffle128() out of sse:: namespace

The implementation is generic.
memory: Rename 'ld_unpack' to 'mem_unpack' and 'st_pack' to 'mem_pack'

These operations do not do any loads and stores themselves. Reflect this
in their name.
memory: Replace 'shuffe_epi8_wrapper' with equivalent 'permute_bytes16'
memory: Move mem_pack* and mem_unpack* out of sse:: namespace

These functions are already implemented in instruction-set independent
way.
transpose: Move several functions out of sse:: namespace

These functions are already implemented in instruction-set independent
way.
test: Add tests for blend()
shuffle: Reduce code duplication in the implementations of blend()
shuffle: Fix a bug in NEON implementation of blend()
transpose: Add 8-bit transpose2 as implementation detail
transpose: Prefer not to use arch-specific functionality where possible
cast: Implement bit_cast() in less undefined way