UniSIMD assembler 1.0.0

UniSIMD provides a unified and low-level macro assembler for ARM and x86 architectures. It declares a subset of shared SIMD instructions and a common API to reduce code deduplication and variation. Currently Intel SSE2 (32-bit x86 ISA) and ARM NEON (32-bit ARMv7 ISA) are supported. 64-bit wide SIMD with longer registers and adressing will be added later. UniSIMD is a C/C++ macro collection, thus can be easily included from header files.