cmake: Fix header installation path
Do not include debian/ directory per Debian guidelines
README: Mention that boost is not a requirement if dispatcher is not used
memory: Add alignment annotations

In NEON, the load/save intrinsics does not have a way to express the
alignment of arguments. This results in the compiler assuming the worst
case and using instructions for unaligned access, which are roughly two
times slower than normal instructions. This commit adds annotations that
inform the compiler about our interface restrictions. Currently only GCC
(>4.7.0) is supported.
memory: Use vst1q_u64 instead of vst1q_u32 for aligned store on NEON

This gives compiler more information about the alignment of the argument
if the compiler does not support alignment annotations.
memory: Use NULL impl for load/store on NEON and Altivec

NEON and Altivec effectively a separate CPU domain for 64-bit FP
operations. Using integer instructions to load and store data will
deliver worse performance due to cross-domain data transfers.